U.S. patent application number 17/394077 was filed with the patent office on 2022-02-10 for method and apparatus for coordinating and allocating sidelink resource.
This patent application is currently assigned to ELECTRONICS AND TELECOMMUNICATIONS RESEARCH INSTITUTE. The applicant listed for this patent is ELECTRONICS AND TELECOMMUNICATIONS RESEARCH INSTITUTE. Invention is credited to Cheul Soon KIM, Jung Hoon LEE, Sung Hyun MOON.
Application Number | 20220046594 17/394077 |
Document ID | / |
Family ID | |
Filed Date | 2022-02-10 |
United States Patent
Application |
20220046594 |
Kind Code |
A1 |
LEE; Jung Hoon ; et
al. |
February 10, 2022 |
METHOD AND APPARATUS FOR COORDINATING AND ALLOCATING SIDELINK
RESOURCE
Abstract
An operation method of a transmitting terminal in a
communication system may comprise: receiving resource coordination
information; selecting a resource for sidelink communication based
on the resource coordination information; and transmitting data to
one or more receiving terminals by using the selected resource,
wherein the resource coordination information is one of information
on a preferred resource and information on a non-preferred resource
for the sidelink communication.
Inventors: |
LEE; Jung Hoon; (Daejeon,
KR) ; KIM; Cheul Soon; (Daejeon, KR) ; MOON;
Sung Hyun; (Daejeon, KR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
ELECTRONICS AND TELECOMMUNICATIONS RESEARCH INSTITUTE |
Daejeon |
|
KR |
|
|
Assignee: |
ELECTRONICS AND TELECOMMUNICATIONS
RESEARCH INSTITUTE
Daejeon
KR
|
Appl. No.: |
17/394077 |
Filed: |
August 4, 2021 |
International
Class: |
H04W 72/02 20060101
H04W072/02; H04W 72/04 20060101 H04W072/04; H04W 72/10 20060101
H04W072/10 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 7, 2020 |
KR |
10-2020-0099489 |
Oct 19, 2020 |
KR |
10-2020-0135558 |
Jan 18, 2021 |
KR |
10-2021-0007072 |
May 11, 2021 |
KR |
10-2021-0060925 |
Jul 19, 2021 |
KR |
10-2021-0094344 |
Claims
1. An operation method of a transmitting terminal in a
communication system, the operation method comprising: receiving
resource coordination information; selecting a resource for
sidelink communication based on the resource coordination
information; and transmitting data to one or more receiving
terminals by using the selected resource, wherein the resource
coordination information is one of information on a preferred
resource and information on a non-preferred resource for the
sidelink communication.
2. The operation method according to claim 1, further comprising
receiving an indicator indicating that the resource coordination
information is the information on a preferred resource or the
information on a non-preferred resource.
3. The operation method according to claim 1, wherein when the
resource coordination information is the information on a preferred
resource, the resource for sidelink communication is selected
within a first resource region indicated by the resource
coordination information.
4. The operation method according to claim 1, wherein when the
resource coordination information is the information on a
non-preferred resource, the resource for sidelink communication is
selected within resources other than a first resource region
indicated by the resource coordination information.
5. The operation method according to claim 1, wherein the selecting
of the resource for sidelink communication comprises: performing a
resource sensing operation; and when an overlapped resource between
a first resource region indicated by the resource coordination
information and a second resource region according to a result of
the resource sensing operation exists, selecting the overlapped
resource for sidelink communication within the first resource
region or the second resource region.
6. The operation method according to claim 5, wherein the selecting
of the resource for sidelink communication comprises: when the
first resource region is different from the second resource region
and a priority of the resource coordination information is higher
than a priority of the result of the resource sensing operation,
selecting preferentially the resource for sidelink communication
within the first resource region.
7. The operation method according to claim 5, wherein the selecting
of the resource for sidelink communication comprises: when the
first resource region is different from the second resource region
and a priority of the resource coordination information is lower
than a priority of the result of the resource sensing operation,
selecting preferentially the resource for sidelink communication
within the second resource region.
8. The operation method according to claim 5, further comprising
receiving a message including at least one of information on a
priority of the resource coordination information and information
on a priority of the result of the resource sensing operation.
9. The operation method according to claim 1, wherein a maximum
number of resource regions indicated by the resource coordination
information is three or more.
10. The operation method according to claim 1, wherein a size of a
subchannel indicated by the resource coordination information is
configured to be different from a size of a subchannel through
which the data is transmitted and received.
11. The operation method according to claim 1, wherein a resource
pool indicated by the resource coordination information is
independently configured, and the resource coordination information
is received in the resource pool.
12. The operation method according to claim 1, wherein the resource
coordination information has a high priority so that a transmission
resource of the resource coordination information is not
pre-empted.
13. The operation method according to claim 1, further comprising
periodically receiving updated resource coordination
information.
14. The operation method according to claim 1, further comprising
receiving updated resource coordination information according to an
occurrence of an event or an update request.
15. A transmitting terminal, the transmitting terminal comprising:
a processor; a memory electronically communicating with the
processor; and instructions stored in the memory, wherein when
executed by the processor, the instructions cause the transmitting
terminal to: receive resource coordination information; select a
resource for sidelink communication based on the resource
coordination information; and transmit data to one or more
receiving terminals by using the selected resource, wherein the
resource coordination information is one of information on a
preferred resource and information on a non-preferred resource for
the sidelink communication.
16. The transmitting terminal according to claim 15, wherein the
instructions further cause the transmitting terminal to receive an
indicator indicating that the resource coordination information is
the information on a preferred resource or the information on a
non-preferred resource, wherein when the resource coordination
information is the information on a preferred resource, the
resource for sidelink communication is selected within a first
resource region indicated by the resource coordination information,
and when the resource coordination information is the information
on a non-preferred resource, the resource for sidelink
communication is selected within resources other than a first
resource region indicated by the resource coordination
information.
17. The transmitting terminal according to claim 15, wherein in the
selecting of the resource for sidelink communication, the
instructions further cause the transmitting terminal to: perform a
resource sensing operation; and when an overlapped resource between
a first resource region indicated by the resource coordination
information and a second resource region according to a result of
the resource sensing operation exists, select the overlapped
resource for sidelink communication within the first resource
region or the second resource region.
18. The transmitting terminal according to claim 17, wherein in the
selecting of the resource for sidelink communication, the
instructions further cause the transmitting terminal to: when the
first resource region is different from the second resource region
and a priority of the resource coordination information is higher
than a priority of the result of the resource sensing operation,
select preferentially the resource for sidelink communication
within the first resource region.
19. The transmitting terminal according to claim 17, wherein in the
selecting of the resource for sidelink communication, the
instructions further cause the transmitting terminal to: when the
first resource region is different from the second resource region
and a priority of the resource coordination information is lower
than a priority of the result of the resource sensing operation,
select preferentially the resource for sidelink communication
within the second resource region.
20. The transmitting terminal according to claim 15, wherein a
maximum number of resource regions indicated by the resource
coordination information is three or more, and a size of a
subchannel indicated by the resource coordination information is
configured to be different from a size of a subchannel through
which the data is transmitted and received.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority to Korean Patent
Applications No. 10-2020-0099489 filed on Aug. 7, 2020, No.
10-2020-0135558 filed on Oct. 19, 2020, No. 10-2021-0007072 filed
on Jan. 18, 2021, No. 10-2021-0060925 filed on May 11, 2021, and
No. 10-2021-0094344 filed on Jul. 19, 2021 with the Korean
Intellectual Property Office (KIPO), the entire contents of which
are hereby incorporated by reference.
BACKGROUND
1. Technical Field
[0002] The present disclosure relates to a sidelink communication
technique in a communication system, and more specifically, to a
technique for coordinating and allocating sidelink resources.
2. Related Art
[0003] The communication system (e.g., a new radio (NR)
communication system) using a higher frequency band (e.g., a
frequency band of 6 GHz or above) than a frequency band (e.g., a
frequency band of 6 GHz or below) of the long term evolution (LTE)
communication system (or, LTE-A communication system) is being
considered for processing of soaring wireless data. The NR system
may support not only a frequency band of 6 GHz or below, but also a
frequency band of 6 GHz or above, and may support various
communication services and scenarios compared to the LTE system. In
addition, requirements of the NR system may include enhanced Mobile
BroadBand (eMBB), Ultra Reliable Low Latency Communication (URLLC),
and Massive Machine Type Communication (mMTC).
[0004] Sidelink communication may be performed in the NR system.
The sidelink communication may be performed based on mode 1 or mode
2. When the mode 1 is used, the sidelink communication may be
performed using a resource scheduled by a base station. When the
mode 2 is used, the sidelink communication may be performed using a
resource selected by a terminal. In this case, if the same resource
is selected by a plurality of terminals, the sidelink communication
may collide. A method is needed to solve these problems.
SUMMARY
[0005] Accordingly, exemplary embodiments of the present disclosure
are directed to providing methods and apparatuses for coordinating
and allocating sidelink resources.
[0006] According to a first exemplary embodiment of the present
disclosure, an operation method of a transmitting terminal in a
communication system may comprise: receiving resource coordination
information; selecting a resource for sidelink communication based
on the resource coordination information; and transmitting data to
one or more receiving terminals by using the selected resource,
wherein the resource coordination information is one of information
on a preferred resource and information on a non-preferred resource
for the sidelink communication.
[0007] The operation method may further comprise receiving an
indicator indicating that the resource coordination information is
the information on a preferred resource or the information on a
non-preferred resource.
[0008] When the resource coordination information is the
information on a preferred resource, the resource for sidelink
communication may be selected within a first resource region
indicated by the resource coordination information.
[0009] When the resource coordination information is the
information on a non-preferred resource, the resource for sidelink
communication may be selected within resources other than a first
resource region indicated by the resource coordination
information.
[0010] The selecting of the resource for sidelink communication may
comprise: performing a resource sensing operation; and when an
overlapped resource between a first resource region indicated by
the resource coordination information and a second resource region
according to a result of the resource sensing operation exists,
selecting the overlapped resource for sidelink communication within
the first resource region or the second resource region.
[0011] The selecting of the resource for sidelink communication may
comprise: when the first resource region is different from the
second resource region and a priority of the resource coordination
information is higher than a priority of the result of the resource
sensing operation, selecting preferentially the resource for
sidelink communication within the first resource region.
[0012] The selecting of the resource for sidelink communication may
comprise: when the first resource region is different from the
second resource region and a priority of the resource coordination
information is lower than a priority of the result of the resource
sensing operation, selecting preferentially the resource for
sidelink communication within the second resource region.
[0013] The operation method may further comprise receiving a
message including at least one of information on a priority of the
resource coordination information and information on a priority of
the result of the resource sensing operation.
[0014] The maximum number of resource regions indicated by the
resource coordination information may be three or more.
[0015] The size of a subchannel indicated by the resource
coordination information may be configured to be different from the
size of a subchannel through which the data is transmitted and
received.
[0016] A resource pool indicated by the resource coordination
information may be independently configured, and the resource
coordination information may be received in the resource pool.
[0017] The resource coordination information may have a high
priority so that a transmission resource of the resource
coordination information may not be pre-empted.
[0018] The operation method may further comprise periodically
receiving updated resource coordination information.
[0019] The operation method may further comprise receiving updated
resource coordination information according to an occurrence of an
event or an update request.
[0020] According to a second exemplary embodiment of the present
disclosure, a transmitting terminal may comprise a processor; a
memory electronically communicating with the processor; and
instructions stored in the memory. In addition, when executed by
the processor, the instructions may cause the transmitting terminal
to: receive resource coordination information; select a resource
for sidelink communication based on the resource coordination
information; and transmit data to one or more receiving terminals
by using the selected resource, wherein the resource coordination
information is one of information on a preferred resource and
information on a non-preferred resource for the sidelink
communication.
[0021] The instructions may further cause the transmitting terminal
to receive an indicator indicating that the resource coordination
information is the information on a preferred resource or the
information on a non-preferred resource, wherein when the resource
coordination information is the information on a preferred
resource, the resource for sidelink communication may be selected
within a first resource region indicated by the resource
coordination information, and when the resource coordination
information is the information on a non-preferred resource, the
resource for sidelink communication may be selected within
resources other than a first resource region indicated by the
resource coordination information.
[0022] In the selecting of the resource for sidelink communication,
the instructions may further cause the transmitting terminal to:
perform a resource sensing operation; and when an overlapped
resource between a first resource region indicated by the resource
coordination information and a second resource region according to
a result of the resource sensing operation exists, select the
overlapped resource for sidelink communication within the first
resource region or the second resource region.
[0023] In the selecting of the resource for sidelink communication,
the instructions may further cause the transmitting terminal to:
when the first resource region is different from the second
resource region and a priority of the resource coordination
information is higher than a priority of the result of the resource
sensing operation, select preferentially the resource for sidelink
communication within the first resource region.
[0024] In the selecting of the resource for sidelink communication,
the instructions may further cause the transmitting terminal to:
when the first resource region is different from the second
resource region and a priority of the resource coordination
information is lower than a priority of the result of the resource
sensing operation, select preferentially the resource for sidelink
communication within the second resource region.
[0025] The maximum number of resource regions indicated by the
resource coordination information may be three or more, and the
size of a subchannel indicated by the resource coordination
information may be configured to be different from the size of a
subchannel through which the data is transmitted and received.
[0026] According to the exemplary embodiments, even when sidelink
communication is performed based on the mode 2, sidelink resources
may be coordinated. That is, in order to prevent resource
collisions between terminals, sidelink resources may be
coordinated. The sidelink communication may be performed based on
the coordinated resources, and thus, the resource collisions
between terminals may be reduced. That is, the performance of the
communication system may be improved. In addition, since a resource
sensing operation and/or resource selection operation may be
performed within restricted resources (e.g., coordinated
resources), energy efficiency may be improved.
BRIEF DESCRIPTION OF DRAWINGS
[0027] FIG. 1 is a conceptual diagram illustrating a first
exemplary embodiment of a communication system.
[0028] FIG. 2 is a block diagram illustrating a first exemplary
embodiment of a communication node constituting a communication
system.
[0029] FIG. 3 is a conceptual diagram illustrating a first
exemplary embodiment of a type 1 frame.
[0030] FIG. 4 is a conceptual diagram illustrating a first
exemplary embodiment of a type 2 frame.
[0031] FIG. 5 is a conceptual diagram illustrating a first
exemplary embodiment of a transmission method of SS/PBCH block in a
communication system.
[0032] FIG. 6 is a conceptual diagram illustrating a first
exemplary embodiment of an SS/PBCH block in a communication
system.
[0033] FIG. 7 is a conceptual diagram illustrating a second
exemplary embodiment of a method of transmitting SS/PBCH blocks in
a communication system.
[0034] FIG. 8A is a conceptual diagram illustrating an RMSI CORESET
mapping pattern #1 in a communication system.
[0035] FIG. 8B is a conceptual diagram illustrating an RMSI CORESET
mapping pattern #2 in a communication system.
[0036] FIG. 8C is a conceptual diagram illustrating an RMSI CORESET
mapping pattern #3 in a communication system.
[0037] FIG. 9 is a conceptual diagram illustrating exemplary
embodiments of a method for multiplexing a control channel and a
data channel in sidelink communication.
[0038] FIG. 10 is a conceptual diagram illustrating a first
exemplary embodiment of a method for configuring a resource
set(s).
[0039] FIG. 11 is a conceptual diagram illustrating a first
exemplary embodiment of a resource pattern for time and frequency
resources.
[0040] FIG. 12 is a conceptual diagram illustrating a first
exemplary embodiment of configuration of a resource pool for
resource coordination.
[0041] FIG. 13 is a conceptual diagram illustrating a first
exemplary embodiment of a resource configuration method for a
triggering signal and/or a keeping signal.
DETAILED DESCRIPTION OF THE EMBODIMENTS
[0042] Embodiments of the present disclosure are disclosed herein.
However, specific structural and functional details disclosed
herein are merely representative for purposes of describing
embodiments of the present disclosure. Thus, embodiments of the
present disclosure may be embodied in many alternate forms and
should not be construed as limited to embodiments of the present
disclosure set forth herein.
[0043] Accordingly, while the present disclosure is capable of
various modifications and alternative forms, specific embodiments
thereof are shown by way of example in the drawings and will herein
be described in detail. It should be understood, however, that
there is no intent to limit the present disclosure to the
particular forms disclosed, but on the contrary, the present
disclosure is to cover all modifications, equivalents, and
alternatives falling within the spirit and scope of the present
disclosure. Like numbers refer to like elements throughout the
description of the figures.
[0044] It will be understood that, although the terms first,
second, etc. may be used herein to describe various elements, these
elements should not be limited by these terms. These terms are only
used to distinguish one element from another. For example, a first
element could be termed a second element, and, similarly, a second
element could be termed a first element, without departing from the
scope of the present disclosure. As used herein, the term "and/or"
includes any and all combinations of one or more of the associated
listed items.
[0045] It will be understood that when an element is referred to as
being "connected" or "coupled" to another element, it can be
directly connected or coupled to the other element or intervening
elements may be present. In contrast, when an element is referred
to as being "directly connected" or "directly coupled" to another
element, there are no intervening elements present. Other words
used to describe the relationship between elements should be
interpreted in a like fashion (i.e., "between" versus "directly
between," "adjacent" versus "directly adjacent," etc.).
[0046] The terminology used herein is for the purpose of describing
particular embodiments only and is not intended to be limiting of
the present disclosure. As used herein, the singular forms "a,"
"an" and "the" are intended to include the plural forms as well,
unless the context clearly indicates otherwise. It will be further
understood that the terms "comprises," "comprising," "includes"
and/or "including," when used herein, specify the presence of
stated features, integers, steps, operations, elements, and/or
components, but do not preclude the presence or addition of one or
more other features, integers, steps, operations, elements,
components, and/or groups thereof.
[0047] Unless otherwise defined, all terms (including technical and
scientific terms) used herein have the same meaning as commonly
understood by one of ordinary skill in the art to which this
present disclosure belongs. It will be further understood that
terms, such as those defined in commonly used dictionaries, should
be interpreted as having a meaning that is consistent with their
meaning in the context of the relevant art and will not be
interpreted in an idealized or overly formal sense unless expressly
so defined herein.
[0048] Hereinafter, exemplary embodiments of the present disclosure
will be described in greater detail with reference to the
accompanying drawings. In order to facilitate general understanding
in describing the present disclosure, the same components in the
drawings are denoted with the same reference signs, and repeated
description thereof will be omitted.
[0049] A communication system to which exemplary embodiments
according to the present disclosure are applied will be described.
The communication system to which the exemplary embodiments
according to the present disclosure are applied is not limited to
the contents described below, and the exemplary embodiments
according to the present disclosure may be applied to various
communication systems. Here, the communication system may be used
in the same sense as a communication network.
[0050] FIG. 1 is a conceptual diagram illustrating a first
exemplary embodiment of a communication system.
[0051] As shown in FIG. 1, a communication system 100 may comprise
a plurality of communication nodes 110-1, 110-2, 110-3, 120-1,
120-2, 130-1, 130-2, 130-3, 130-4, 130-5, and 130-6. Also, the
communication system 100 may further comprise a core network (e.g.,
a serving gateway (S-GW), a packet data network (PDN) gateway
(P-GW), and a mobility management entity (MME)). When the
communication system 100 is a 5G communication system (e.g., new
radio (NR) system), the core network may include an access and
mobility management function (AMF), a user plane function (UPF), a
session management function (SMF), and the like.
[0052] The plurality of communication nodes 110 to 130 may support
a communication protocol defined by the 3rd generation partnership
project (3GPP) specifications (e.g., LTE communication protocol,
LTE-A communication protocol, NR communication protocol, or the
like). The plurality of communication nodes 110 to 130 may support
code division multiple access (CDMA) technology, wideband CDMA
(WCDMA) technology, time division multiple access (TDMA)
technology, frequency division multiple access (FDMA) technology,
orthogonal frequency division multiplexing (OFDM) technology,
filtered OFDM technology, cyclic prefix OFDM (CP-OFDM) technology,
discrete Fourier transform-spread-OFDM (DFT-s-OFDM) technology,
orthogonal frequency division multiple access (OFDMA) technology,
single carrier FDMA (SC-FDMA) technology, non-orthogonal multiple
access (NOMA) technology, generalized frequency division
multiplexing (GFDM) technology, filter band multi-carrier (FBMC)
technology, universal filtered multi-carrier (UFMC) technology,
space division multiple access (SDMA) technology, or the like. Each
of the plurality of communication nodes may have the following
structure.
[0053] FIG. 2 is a block diagram illustrating a first exemplary
embodiment of a communication node constituting a communication
system.
[0054] Referring to FIG. 2, a communication node 200 may comprise
at least one processor 210, a memory 220, and a transceiver 230
connected to the network for performing communications. Also, the
communication node 200 may further comprise an input interface
device 240, an output interface device 250, a storage device 260,
and the like. Each component included in the communication node 200
may communicate with each other as connected through a bus 270.
[0055] However, each component included in the communication node
200 may not be connected to the common bus 270 but may be connected
to the processor 210 via an individual interface or a separate bus.
For example, the processor 210 may be connected to at least one of
the memory 220, the transceiver 230, the input interface device
240, the output interface device 250 and the storage device 260 via
a dedicated interface.
[0056] The processor 210 may execute a program stored in at least
one of the memory 220 and the storage device 260. The processor 210
may refer to a central processing unit (CPU), a graphics processing
unit (GPU), or a dedicated processor on which methods in accordance
with embodiments of the present disclosure are performed. Each of
the memory 220 and the storage device 260 may be constituted by at
least one of a volatile storage medium and a non-volatile storage
medium. For example, the memory 220 may comprise at least one of
read-only memory (ROM) and random access memory (RAM).
[0057] Referring again to FIG. 1, the communication system 100 may
comprise a plurality of base stations 110-1, 110-2, 110-3, 120-1,
and 120-2, and a plurality of terminals 130-1, 130-2, 130-3, 130-4,
130-5, and 130-6. Each of the first base station 110-1, the second
base station 110-2, and the third base station 110-3 may form a
macro cell, and each of the fourth base station 120-1 and the fifth
base station 120-2 may form a small cell. The fourth base station
120-1, the third terminal 130-3, and the fourth terminal 130-4 may
belong to cell coverage of the first base station 110-1. Also, the
second terminal 130-2, the fourth terminal 130-4, and the fifth
terminal 130-5 may belong to cell coverage of the second base
station 110-2. Also, the fifth base station 120-2, the fourth
terminal 130-4, the fifth terminal 130-5, and the sixth terminal
130-6 may belong to cell coverage of the third base station 110-3.
Also, the first terminal 130-1 may belong to cell coverage of the
fourth base station 120-1, and the sixth terminal 130-6 may belong
to cell coverage of the fifth base station 120-2.
[0058] Here, each of the plurality of base stations 110-1, 110-2,
110-3, 120-1, and 120-2 may refer to a Node-B (NB), a evolved
Node-B (eNB), a gNB, an advanced base station (ABS), a high
reliability-base station (HR-BS), a base transceiver station (BTS),
a radio base station, a radio transceiver, an access point, an
access node, a radio access station (RAS), a mobile multihop
relay-base station (MMR-BS), a relay station (RS), an advanced
relay station (ARS), a high reliability-relay station (HR-RS), a
home NodeB (HNB), a home eNodeB (HeNB), a road side unit (RSU), a
radio remote head (RRH), a transmission point (TP), a transmission
and reception point (TRP), or the like.
[0059] Each of the plurality of terminals 130-1, 130-2, 130-3,
130-4, 130-5, and 130-6 may refer to a user equipment (UE), a
terminal equipment (TE), an advanced mobile station (AMS), a high
reliability-mobile station (HR-MS), a terminal, an access terminal,
a mobile terminal, a station, a subscriber station, a mobile
station, a portable subscriber station, a node, a device, an
on-board unit (OBU), or the like.
[0060] Meanwhile, each of the plurality of base stations 110-1,
110-2, 110-3, 120-1, and 120-2 may operate in the same frequency
band or in different frequency bands. The plurality of base
stations 110-1, 110-2, 110-3, 120-1, and 120-2 may be connected to
each other via an ideal backhaul or a non-ideal backhaul, and
exchange information with each other via the ideal or non-ideal
backhaul. Also, each of the plurality of base stations 110-1,
110-2, 110-3, 120-1, and 120-2 may be connected to the core network
through the ideal or non-ideal backhaul. Each of the plurality of
base stations 110-1, 110-2, 110-3, 120-1, and 120-2 may transmit a
signal received from the core network to the corresponding terminal
130-1, 130-2, 130-3, 130-4, 130-5, or 130-6, and transmit a signal
received from the corresponding terminal 130-1, 130-2, 130-3,
130-4, 130-5, or 130-6 to the core network.
[0061] Also, each of the plurality of base stations 110-1, 110-2,
110-3, 120-1, and 120-2 may support a multi-input multi-output
(MIMO) transmission (e.g., a single-user MIMO (SU-MIMO), a
multi-user MIMO (MU-MIMO), a massive MIMO, or the like), a
coordinated multipoint (CoMP) transmission, a carrier aggregation
(CA) transmission, a transmission in unlicensed band,
device-to-device (D2D) communication (or, proximity services
(ProSe)), Internet of Things (IoT) communications, dual
connectivity (DC), or the like. Here, each of the plurality of
terminals 130-1, 130-2, 130-3, 130-4, 130-5, and 130-6 may perform
operations corresponding to the operations of the plurality of base
stations 110-1, 110-2, 110-3, 120-1, and 120-2 (i.e., the
operations supported by the plurality of base stations 110-1,
110-2, 110-3, 120-1, and 120-2). For example, the second base
station 110-2 may transmit a signal to the fourth terminal 130-4 in
the SU-MIMO manner, and the fourth terminal 130-4 may receive the
signal from the second base station 110-2 in the SU-MIMO manner.
Alternatively, the second base station 110-2 may transmit a signal
to the fourth terminal 130-4 and fifth terminal 130-5 in the
MU-MIMO manner, and the fourth terminal 130-4 and fifth terminal
130-5 may receive the signal from the second base station 110-2 in
the MU-MIMO manner.
[0062] The first base station 110-1, the second base station 110-2,
and the third base station 110-3 may transmit a signal to the
fourth terminal 130-4 in the CoMP transmission manner, and the
fourth terminal 130-4 may receive the signal from the first base
station 110-1, the second base station 110-2, and the third base
station 110-3 in the CoMP manner. Also, each of the plurality of
base stations 110-1, 110-2, 110-3, 120-1, and 120-2 may exchange
signals with the corresponding terminals 130-1, 130-2, 130-3,
130-4, 130-5, or 130-6 which belongs to its cell coverage in the CA
manner. Each of the base stations 110-1, 110-2, and 110-3 may
control D2D communications between the fourth terminal 130-4 and
the fifth terminal 130-5, and thus the fourth terminal 130-4 and
the fifth terminal 130-5 may perform the D2D communications under
control of the second base station 110-2 and the third base station
110-3.
[0063] Meanwhile, the communication system may support three types
of frame structures. A type 1 frame structure may be applied to a
frequency division duplex (FDD) communication system, a type 2
frame structure may be applied to a time division duplex (TDD)
communication system, and a type 3 frame structure may be applied
to an unlicensed band based communication system (e.g., a licensed
assisted access (LAA) communication system).
[0064] FIG. 3 is a conceptual diagram illustrating a first
exemplary embodiment of a type 1 frame.
[0065] Referring to FIG. 3, a radio frame 300 may comprise 10
subframes, and a subframe may comprise 2 slots. Thus, the radio
frame 300 may comprise 20 slots (e.g., slot #0, slot #1, slot #2,
slot #3, . . . , slot #18, and slot #19). The length T.sub.f of the
radio frame 300 may be 10 milliseconds (ms). The length of the
subframe may be 1 ms, and the length T.sub.oot of a slot may be 0.5
ms. Here, T.sub.s may indicate a sampling time, and may be
1/30,720,000 s.
[0066] The slot may be composed of a plurality of OFDM symbols in
the time domain, and may be composed of a plurality of resource
blocks (RBs) in the frequency domain. The RB may be composed of a
plurality of subcarriers in the frequency domain. The number of
OFDM symbols constituting the slot may vary depending on
configuration of a cyclic prefix (CP). The CP may be classified
into a normal CP and an extended CP. If the normal CP is used, the
slot may be composed of 7 OFDM symbols, in which case the subframe
may be composed of 14 OFDM symbols. If the extended CP is used, the
slot may be composed of 6 OFDM symbols, in which case the subframe
may be composed of 12 OFDM symbols.
[0067] FIG. 4 is a conceptual diagram illustrating a first
exemplary embodiment of a type 2 frame.
[0068] Referring to FIG. 4, a radio frame 400 may comprise two half
frames, and a half frame may comprise 5 subframes. Thus, the radio
frame 400 may comprise 10 subframes. The length T.sub.f of the
radio frame 400 may be 10 ms. The length of the half frame may be 5
ms. The length of the subframe may be 1 ms. Here, T.sub.s may be
1/30,720,000 s.
[0069] The radio frame 400 may include at least one downlink
subframe, at least one uplink subframe, and a least one special
subframe. Each of the downlink subframe and the uplink subframe may
include two slots. The length T.sub.slot of a slot may be 0.5 ms.
Among the subframes included in the radio frame 400, each of the
subframe #1 and the subframe #6 may be a special subframe. For
example, when a switching periodicity between downlink and uplink
is 5 ms, the radio frame 400 may include 2 special subframes.
Alternatively, the switching periodicity between downlink and
uplink is 10 ms, the radio frame 400 may include one special
subframe. The special subframe may include a downlink pilot time
slot (DwPTS), a guard period (GP), and an uplink pilot time slot
(UpPTS).
[0070] The downlink pilot time slot may be regarded as a downlink
interval and may be used for cell search, time and frequency
synchronization acquisition of the terminal, channel estimation,
and the like. The guard period may be used for resolving
interference problems of uplink data transmission caused by delay
of downlink data reception. Also, the guard period may include a
time required for switching from the downlink data reception
operation to the uplink data transmission operation. The uplink
pilot time slot may be used for uplink channel estimation, time and
frequency synchronization acquisition, and the like. Transmission
of a physical random access channel (PRACH) or a sounding reference
signal (SRS) may be performed in the uplink pilot time slot.
[0071] The lengths of the downlink pilot time slot, the guard
period, and the uplink pilot time slot included in the special
subframe may be variably adjusted as needed. In addition, the
number and position of each of the downlink subframe, the uplink
subframe, and the special subframe included in the radio frame 400
may be changed as needed.
[0072] In the communication system, a transmission time interval
(TTI) may be a basic time unit for transmitting coded data through
a physical layer. A short TTI may be used to support low latency
requirements in the communication system. The length of the short
TTI may be less than 1 ms. The conventional TTI having a length of
1 ms may be referred to as a base TTI or a regular TTI. That is,
the base TTI may be composed of one subframe. In order to support
transmission on a base TTI basis, signals and channels may be
configured on a subframe basis. For example, a cell-specific
reference signal (CRS), a physical downlink control channel
(PDCCH), a physical downlink shared channel (PDSCH), a physical
uplink control channel (PUCCH), a physical uplink shared channel
(PUSCH), and the like may exist in each subframe.
[0073] On the other hand, a synchronization signal (e.g., a primary
synchronization signal (PSS) and a secondary synchronization signal
(SSS)) may exist for every 5 subframes, and a physical broadcast
channel (PBCH) may exist for every 10 subframes. Also, each radio
frame may be identified by an SFN, and the SFN may be used for
defining transmission of a signal (e.g., a paging signal, a
reference signal for channel estimation, a signal for channel state
information, etc.) longer than one radio frame. The periodicity of
the SFN may be 1024.
[0074] In the LTE system, the PBCH may be a physical layer channel
used for transmission of system information (e.g., master
information block (MIB)). The PBCH may be transmitted every 10
subframes. That is, the transmission periodicity of the PBCH may be
10 ms, and the PBCH may be transmitted once in the radio frame. The
same MIB may be transmitted during 4 consecutive radio frames, and
after 4 consecutive radio frames, the MIB may be changed according
to a situation of the LTE system. The transmission period for which
the same MIB is transmitted may be referred to as a `PBCH TTI`, and
the PBCH TTI may be 40 ms. That is, the MIB may be changed for each
PBCH TTI.
[0075] The MIB may be composed of 40 bits. Among the 40 bits
constituting the MIB, 3 bits may be used to indicate a system band,
3 bits may be used to indicate physical hybrid automatic repeat
request (ARQ) indicator channel (PHICH) related information, 8 bits
may be used to indicate an SFN, 10 bits may be configured as
reserved bits, and 16 bits may be used for a cyclic redundancy
check (CRC).
[0076] The SFN for identifying the radio frame may be composed of a
total of 10 bits (B9 to B0), and the most significant bits (MSBs) 8
bits (B9 to B2) among the 10 bits may be indicated by the PBCH
(i.e., MIB). The MSBs 8 bits (B9 to B2) of the SFN indicated by the
PBCH (i.e., MIB) may be identical during 4 consecutive radio frames
(i.e., PBCH TTI). The least significant bits (LSBs) 2 bits (B1 to
B0) of the SFN may be changed during 4 consecutive radio frames
(i.e., PBCH TTI), and may not be explicitly indicated by the PBCH
(i.e., MIB). The LSBs (2 bits (B1 to B0)) of the SFN may be
implicitly indicated by a scrambling sequence of the PBCH
(hereinafter referred to as `PBCH scrambling sequence`).
[0077] A Gold sequence generated by being initialized by a cell ID
may be used as the PBCH scrambling sequence, and the PBCH
scrambling sequence may be initialized for each four consecutive
radio frames (e.g., each PBCH TTI) based on an operation of `mod
(SFN, 4)`. The PBCH transmitted in a radio frame corresponding to
an SFN with LSBs 2 bits (B1 to B0) set to `00` may be scrambled by
the Gold sequence generated by being initialized by the cell ID.
Thereafter, the Gold sequences generated according to the operation
of `mod (SFN, 4)` may be used to scramble the PBCH transmitted in
the radio frames corresponding to SFNs with LSBs 2 bits (B1 to B0)
set to `01`, `10`, and `11`.
[0078] Accordingly, the terminal having acquired the cell ID in the
initial cell search process may identify the value of the LSBs 2
bits (B1 to B0) of the SFN (e.g., `00`, `01`, `10`, or `11`) based
on the PBCH scramble sequence obtained in the decoding process for
the PBCH (i.e., MIB). The terminal may use the LSBs 2 bits (B1 to
B0) of the SFN obtained based on the PBCH scrambling sequence and
the MSBs 8 bits (B9 to B2) of the SFN indicated by the PBCH (i.e.,
MIB) so as to identify the SFN (i.e., the entire bits B9 to B0 of
the SFN).
[0079] On the other hand, the communication system may support not
only a high transmission rate but also technical requirements for
various service scenarios. For example, the communication system
may support an enhanced mobile broadband (eMBB) service, an
ultra-reliable low-latency communication (URLLC) service, a massive
machine type communication (mMTC) service, and the like.
[0080] The subcarrier spacing of the communication system (e.g.,
OFDM-based communication system) may be determined based on a
carrier frequency offset (CFO) and the like. The CFO may be
generated by a Doppler effect, a phase drift, or the like, and may
increase in proportion to an operation frequency. Therefore, in
order to prevent the performance degradation of the communication
system due to the CFO, the subcarrier spacing may increase in
proportion to the operation frequency. On the other hand, as the
subcarrier spacing increases, a CP overhead may increase.
Therefore, the subcarrier spacing may be configured based on a
channel characteristic, a radio frequency (RF) characteristic, etc.
according to a frequency band.
[0081] The communication system may support numerologies defined in
Table 1 below.
TABLE-US-00001 TABLE 1 Numerology (.mu.) 0 1 2 3 4 5 Subcarrier 15
kHz 30 kHz 60 kHz 120 kHz 240 kHz 480 kHz spacing OFDM symbol 66.7
33.3 16.7 8.3 4.2 2.1 length [us] CP length [us] 4.76 2.38 1.19
0.60 0.30 0.15 Number of 14 28 56 112 224 448 OFDM symbols within 1
ms
[0082] For example, the subcarrier spacing of the communication
system may be configured to 15 kHz, 30 kHz, 60 kHz, or 120 kHz. The
subcarrier spacing of the LTE system may be 15 kHz, and the
subcarrier spacing of the NR system may be 1, 2, 4, or 8 times the
conventional subcarrier spacing of 15 kHz. If the subcarrier
spacing increases by exponentiation units of 2 of the conventional
subcarrier spacing, the frame structure can be easily designed.
[0083] The communication system may support a wide frequency band
(e.g., several hundred MHz to tens of GHz). Since the diffraction
characteristic and the reflection characteristic of the radio wave
are poor in a high frequency band, a propagation loss (e.g., path
loss, reflection loss, and the like) in a high frequency band may
be larger than a propagation loss in a low frequency band.
Therefore, a cell coverage of a communication system supporting a
high frequency band may be smaller than a cell coverage of a
communication system supporting a low frequency band. In order to
solve such the problem, a beamforming scheme based on a plurality
of antenna elements may be used to increase the cell coverage in
the communication system supporting a high frequency band.
[0084] The beamforming scheme may include a digital beamforming
scheme, an analog beamforming scheme, a hybrid beamforming scheme,
and the like. In the communication system using the digital
beamforming scheme, a beamforming gain may be obtained using a
plurality of RF paths based on a digital precoder or a codebook. In
the communication system using the analog beamforming scheme, a
beamforming gain may be obtained using analog RF devices (e.g.,
phase shifter, power amplifier (PA), variable gain amplifier (VGA),
and the like) and an antenna array.
[0085] Because of the need for expensive digital to analog
converters (DACs) or analog to digital converters (ADCs) for
digital beamforming schemes and transceiver units corresponding to
the number of antenna elements, the complexity of antenna
implementation may be increased to increase the beamforming gain.
In case of the communication system using the analog beamforming
scheme, since a plurality of antenna elements are connected to one
transceiver unit through phase shifters, the complexity of the
antenna implementation may not increase greatly even if the
beamforming gain is increased. However, the beamforming performance
of the communication system using the analog beamforming scheme may
be lower than the beamforming performance of the communication
system using the digital beamforming scheme. Further, in the
communication system using the analog beamforming scheme, since the
phase shifter is adjusted in the time domain, frequency resources
may not be efficiently used. Therefore, a hybrid beam forming
scheme, which is a combination of the digital scheme and the analog
scheme, may be used.
[0086] When the cell coverage is increased by the use of the
beamforming scheme, common control channels and common signals
(e.g., reference signal and synchronization signal) for all
terminals belonging to the cell coverage as well as control
channels and data channels for each terminal may also be
transmitted based on the beamforming scheme. In this case, the
common control channels and the common signals for all terminals
belonging to the cell coverage may be transmitted based on a beam
sweeping scheme.
[0087] Also, in the NR system, a synchronization signal/physical
broadcast channel (SS/PBCH) block may also be transmitted in a beam
sweeping scheme. The SS/PBCH block may be composed of a PSS, an
SSS, a PBCH, and the like. In the SS/PBCH block, the PSS, the SSS,
and the PBCH may be configured in a time division multiplexing
(TDM) manner. The SS/PBCH block may be referred also to as an `SS
block (SSB)`. One SS/PBCH block may be transmitted using N
consecutive OFDM symbols. Here, N may be an integer equal to or
greater than 4. The base station may periodically transmit the
SS/PBCH block, and the terminal may acquire frequency/time
synchronization, a cell ID, system information, and the like based
on the SS/PBCH block received from the base station. The SS/PBCH
block may be transmitted as follows.
[0088] FIG. 5 is a conceptual diagram illustrating a first
exemplary embodiment of a transmission method of SS/PBCH block in a
communication system.
[0089] As shown in FIG. 5, one or more SS/PBCH blocks may be
transmitted in a beam sweeping scheme within an SS/PBCH block burst
set. Up to L SS/PBCH blocks may be transmitted within one SS/PBCH
block burst set. L may be an integer equal to or greater than 2,
and may be defined in the 3GPP standard. Depending on a region of a
system frequency, L may vary. Within the SS/PBCH block burst set,
the SS/PBCH blocks may be located consecutively or distributedly.
The consecutive SS/PBCH blocks may be referred to as an `SS/PBCH
block burst`. The SS/PBCH block burst set may be repeated
periodically, and system information (e.g., MIB) transmitted
through the PBCHs of the SS/PBCH blocks within the SS/PBCH block
burst set may be the same. An index of the SS/PBCH block, an index
of the SS/PBCH block burst, an index of an OFDM symbol, an index of
a slot, and the like may be indicated explicitly or implicitly by
the PBCH.
[0090] FIG. 6 is a conceptual diagram illustrating a first
exemplary embodiment of an SS/PBCH block in a communication
system.
[0091] As shown in FIG. 6, signals and a channel are arranged
within one SS/PBCH block in the order of
`PSS.fwdarw.PBCH.fwdarw.SSS.fwdarw.PBCH`. The PSS, SSS, and PBCH
within the SS/PBCH block may be configured in a TDM scheme. In a
symbol where the SSS is located, the PBCH may be located in
frequency resources above the SSS and frequency resources below the
SSS. That is, the PBCH may be transmitted in both end bands
adjacent to the frequency band in which the SSS is transmitted.
When the maximum number L of SS/PBCH blocks is 8 in the sub 6 GHz
frequency band, an SS/PBCH block index may be identified based on a
demodulation reference signal used for demodulating the PBCH
(hereinafter, referred to as `PBCH DMRS`). When the maximum number
L of SSBs is 64 in the over 6 GHz frequency band, LSB 3 bits of 6
bits representing the SS/PBCH block index may be identified based
on the PBCH DMRS, and the remaining MSB 3 bits may be identified
based on a payload of the PBCH.
[0092] The maximum system bandwidth that can be supported in the NR
system may be 400 MHz. The size of the maximum bandwidth that can
be supported by the terminal may vary depending on the capability
of the terminal. Therefore, the terminal may perform an initial
access procedure (e.g., initial connection procedure) by using some
of the system bandwidth of the NR system supporting a wide band. In
order to support access procedures of terminals supporting various
sizes of bandwidths, SS/PBCH blocks may be multiplexed in the
frequency domain within the system bandwidth of the NR system
supporting a wide band. In this case, the SS/PBCH blocks may be
transmitted as follows.
[0093] FIG. 7 is a conceptual diagram illustrating a second
exemplary embodiment of a method of transmitting SS/PBCH blocks in
a communication system.
[0094] As shown in FIG. 7, a wideband component carrier (CC) may
include a plurality of bandwidth parts (BWPs). For example, the
wideband CC may include 4 BWPs. The base station may transmit
SS/PBCH blocks in the respective BWPs #0 to #3 belonging to the
wideband CC. The terminal may receive the SS/PBCH block(s) from one
or more BWPs of the BWPs #0 to #3, and may perform an initial
access procedure using the received SS/PBCH block.
[0095] After detecting the SS/PBCH block, the terminal may acquire
system information (e.g., remaining minimum system information
(RMSI)), and may perform a cell access procedure based on the
system information. The RMSI may be transmitted on a PDSCH
scheduled by a PDCCH. Configuration information of a control
resource set (CORESET) in which the PDCCH including scheduling
information of the PDSCH through which the RMSI is transmitted may
be transmitted on a PBCH within the SS/PBCH block. A plurality of
SS/PBCH blocks may be transmitted in the entire system band, and
one or more SS/PBCH blocks among the plurality of SS/PBCH blocks
may be SS/PBCH block(s) associated with the RMSI. The remaining
SS/PBCH blocks may not be associated with the RMSI. The SS/PBCH
block associated with the RMSI may be defined as a `cell defining
SS/PBCH block`. The terminal may perform a cell search procedure
and an initial access procedure by using the cell-defining SS/PBCH
block. The SS/PBCH block not associated with the RMSI may be used
for a synchronization procedure and/or a measurement procedure in
the corresponding BWP. The BWP(s) through which the SS/PBCH block
is transmitted may be limited to one or more BWPs within a wide
bandwidth.
[0096] The RMSI may be obtained by performing an operation to
obtain configuration information of a CORESET from the SS/PBCH
block (e.g., PBCH), an operation of detecting a PDCCH based on the
configuration information of the CORESET, an operation to obtain
scheduling information of a PDSCH from the PDCCH, and an operation
to receive the RMSI through the PDSCH. A transmission resource of
the PDCCH may be configured by the configuration information of the
CORESET. A mapping patter of the RMSI CORESET pattern may be
defined as follows. The RMSI CORESET may be a CORESET used for
transmission and reception of the RMSI.
[0097] FIG. 8A is a conceptual diagram illustrating an RMSI CORESET
mapping pattern #1 in a communication system, FIG. 8B is a
conceptual diagram illustrating an RMSI CORESET mapping pattern #2
in a communication system, and FIG. 8C is a conceptual diagram
illustrating an RMSI CORESET mapping pattern #3 in a communication
system.
[0098] As shown in FIGS. 8A to 8C, one RMSI CORESET mapping pattern
among the RMSI CORESET mapping patterns #1 to #3 may be used, and a
detailed configuration according to the one RMSI CORESET mapping
pattern may be determined. In the RMSI CORESET mapping pattern #1,
the SS/PBCH block, the CORESET (i.e., RMSI CORESET), and the PDSCH
(i.e., RMSI PDSCH) may be configured in a TDM scheme. The RMSI
PDSCH may mean the PDSCH through which the RMSI is transmitted. In
the RMSI CORESET mapping pattern #2, the CORESET (i.e., RMSI
CORESET) and the PDSCH (i.e., RMSI PDSCH) may be configured in a
TDM scheme, and the PDSCH (i.e., RMSI PDSCH) and the SS/PBCH block
may be configured in a frequency division multiplexing (FDM)
scheme. In the RMSI CORESET mapping pattern #3, the CORESET (i.e.,
RMSI CORESET) and the PDSCH (i.e., RMSI PDSCH) may be configured in
a TDM scheme, and the CORESET (i.e., RMSI CORESET) and the PDSCH
(i.e., RMSI PDSCH) may be multiplexed with the SS/PBCH block in a
FDM scheme.
[0099] In the frequency band of 6 GHz or below, only the RMSI
CORESET mapping pattern #1 may be used. In the frequency band of 6
GHz or above, all of the RMSI CORESET mapping patterns #1, #2, and
#3 may be used. The numerology of the SS/PBCH block may be
different from that of the RMSI CORESET and the RMSI PDSCH. Here,
the numerology may be a subcarrier spacing. In the RMSI CORESET
mapping pattern #1, a combination of all numerologies may be used.
In the RMSI CORESET mapping pattern #2, a combination of
numerologies (120 kHz, 60 kHz) or (240 kHz, 120 kHz) may be used
for the SS/PBCH block and the RMSI CORESET/PDSCH. In the RMSI
CORESET mapping pattern #3, a combination of numerologies (120 kHz,
120 kHz) may be used for the SS/PBCH block and the RMSI
CORESET/PDSCH.
[0100] One RMSI CORESET mapping pattern may be selected from the
RMSI CORESET mapping patterns #1 to #3 according to the combination
of the numerology of the SS/PBCH block and the numerology of the
RMSI CORESET/PDSCH. The configuration information of the RMSI
CORESET may include Table A and Table B. Table A may represent the
number of resource blocks (RBs) of the RMSI CORESET, the number of
symbols of the RMSI CORESET, and an offset between an RB (e.g.,
starting RB or ending RB) of the SS/PBCH block and an RB (e.g.,
starting RB or ending RB) of the RMSI CORESET. Table B may
represent the number of search space sets per slot, an offset of
the RMSI CORESET, and an OFDM symbol index in each of the RMSI
CORESET mapping patterns. Table B may represent information for
configuring a monitoring occasion of the RMSI PDCCH. Each of Table
A and Table B may be composed of a plurality of sub-tables. For
example, Table A may include sub-tables 13-1 to 13-8 defined in the
technical specification (TS) 38.213, and Table B may include
sub-tables 13-9 to 13-13 defined in the TS 38.213. The size of each
of Table A and Table B may be 4 bits.
[0101] In the NR system, a PDSCH may be mapped to the time domain
according to a PDSCH mapping type A or a PDSCH mapping type B. The
PDSCH mapping types A and B may be defined as Table 2 below.
TABLE-US-00002 TABLE 2 PDSCH mapping Normal CP Extended CP type S L
S + L S L S + L Type A {0, 1, 2, 3} {3, . . ., 14} {3, . . ., 14}
{0, 1, 2, 3} {3, . . ., 12} {3, . . ., 12} (Note 1) (Note 1) Type B
{0, . . ., 12} {2, 4, 7} {2, . . ., 14} {0, . . ., 10} {2, 4, 6}
{2, . . ., 12} Note 1: S = 3 is applicable only if
dmrs-TypeA-Position = 3
[0102] The type A (i.e., PDSCH mapping type A) may be slot-based
transmission. When the type A is used, a position of a start symbol
of a PDSCH may be configured to one of {0, 1, 2, 3}. When the type
A and a normal CP are used, the number of symbols constituting the
PDSCH (e.g., the duration of the PDSCH) may be configured to one of
3 to 14 within a range not exceeding a slot boundary. The type B
(i.e., PDSCH mapping type B) may be non-slot-based transmission.
When the type B is used, a position of a start symbol of a PDSCH
may be configured to one of 0 to 12. When the type B and the normal
CP are used, the number of symbols constituting the PDSCH (e.g.,
the duration of the PDSCH) may be configured to one of {2, 4, 7}
within a range not exceeding a slot boundary. A DMRS (hereinafter,
referred to as `PDSCH DMRS`) for demodulation of the PDSCH (e.g.,
data) may be determined by a value of ID indicating the PDSCH
mapping type (e.g., type A or type B) and the length. The ID may be
defined differently according to the PDSCH mapping type.
[0103] Meanwhile, NR-unlicensed (NR-U) is being discussed in the NR
standardization meeting. The NR-U system may increase network
capacity by improving the utilization of limited frequency
resources. The NR-U system may support operation in an unlicensed
band (e.g., unlicensed spectrum).
[0104] In the NR-U system, the terminal may determine whether a
signal is transmitted from a base station based on a discovery
reference signal (DRS) received from the corresponding base station
in the same manner as in the general NR system. In the NR-U system
in a Stand-Alone (SA) mode, the terminal may acquire
synchronization and/or system information based on the DRS. In the
NR-U system, the DRS may be transmitted according to a regulation
of the unlicensed band (e.g., transmission band, transmission
power, transmission time, etc.). For example, according to Occupied
Channel Bandwidth (OCB) regulations, signals may be configured
and/or transmitted to occupy 80% of the total channel bandwidth
(e.g., 20 MHz).
[0105] In the NR-U system, a communication node (e.g., base
station, terminal) may perform a Listen Before Talk (LBT) procedure
before transmitting a signal and/or a channel for coexistence with
another system. The signal may be a synchronization signal, a
reference signal (e.g., DRS, DMRS, channel state information
(CSI)-RS, phase tracking (PT)-RS, sounding reference signal (SRS)),
or the like. The channel may be a downlink channel, an uplink
channel, a sidelink channel, or the like. In exemplary embodiments,
a signal may mean the `signal`, the `channel`, or the `signal and
channel`. The LBT procedure may be an operation for checking
whether a signal is transmitted by another communication node. If
it is determined by the LBT procedure that there is no transmission
signal (e.g., when the LBT procedure is successful), the
communication node may transmit a signal in the unlicensed band. If
it is determined by the LBT procedure that a transmission signal
exists (e.g., when the LBT fails), the communication node may not
be able to transmit a signal in the unlicensed band. The
communication node may perform a LBT procedure according to one of
various categories before transmission of a signal. The category of
LBT may vary depending on the type of the transmission signal.
[0106] Meanwhile, NR vehicle-to-everything (V2X) communication
technology is being discussed in the NR standardization meeting.
The NR V2X communication technology may be a technology that
supports communication between vehicles, communication between a
vehicle and an infrastructure, communication between a vehicle and
a pedestrian, and the like based on device-to-device (D2D)
communication technologies.
[0107] The NR V2X communication (e.g., sidelink communication) may
be performed according to three transmission schemes (e.g., unicast
scheme, broadcast scheme, groupcast scheme). When the unicast
scheme is used, a PC5-RRC connection may be established between a
first terminal (e.g. transmitting terminal that transmits data) and
a second terminal (e.g., receiving terminal that receives data),
and the PC5-RRC connection may refer to a logical connection for a
pair between a source ID of the first terminal and a destination ID
of the second terminal. The first terminal may transmit data (e.g.,
sidelink data) to the second terminal. When the broadcast scheme is
used, the first terminal may transmit data to all terminals. When
the groupcast scheme is used, the first terminal may transmit data
to a group (e.g., groupcast group) composed of a plurality of
terminals.
[0108] When the unicast scheme is used, the second terminal may
transmit feedback information (e.g., acknowledgment (ACK) or
negative ACK (NACK)) to the first terminal in response to data
received from the first terminal. In the exemplary embodiments
below, the feedback information may be referred to as a `HARQ-ACK`,
`feedback signal`, a `physical sidelink feedback channel (PSFCH)
signal`, or the like. When ACK is received from the second
terminal, the first terminal may determine that the data has been
successfully received at the second terminal. When NACK is received
from the second terminal, the first terminal may determine that the
second terminal has failed to receive the data. In this case, the
first terminal may transmit additional information to the second
terminal based on an HARQ scheme. Alternatively, the first terminal
may improve a reception probability of the data at the second
terminal by retransmitting the same data to the second
terminal.
[0109] When the broadcast scheme is used, a procedure for
transmitting feedback information for data may not be performed.
For example, system information may be transmitted in the broadcast
scheme, and the terminal may not transmit feedback information for
the system information to the base station. Therefore, the base
station may not identify whether the system information has been
successfully received at the terminal. To solve this problem, the
base station may periodically broadcast the system information.
[0110] When the groupcast scheme is used, a procedure for
transmitting feedback information for data may not be performed.
For example, necessary information may be periodically transmitted
in the groupcast scheme, without the procedure for transmitting
feedback information. However, when the candidates of terminals
participating in the groupcast scheme-based communication and/or
the number of the terminals participating in that is limited, and
the data transmitted in the groupcast scheme is data that should be
received within a preconfigured time (e.g., data sensitive to
delay), it may be necessary to transmit feedback information also
in the groupcast sidelink communication. The groupcast sidelink
communication may mean sidelink communication performed in the
groupcast scheme. When the feedback information transmission
procedure is performed in the groupcast sidelink communication,
data can be transmitted and received efficiently and reliably.
[0111] In the groupcast sidelink communication, two HARQ-ACK
feedback schemes (i.e., transmission procedures of feedback
information) may be supported. When the number of receiving
terminals in a sidelink group is large and a service scenario 1 is
supported, some receiving terminals belonging to a specific range
within the sidelink group may transmit NACK through a PSFCH when
data reception fails. This scheme may be a groupcast HARQ-ACK
feedback option 1. In the service scenario 1, instead of all the
receiving terminals in the sidelink group, it may be allowed for
some receiving terminals belonging to a specific range to perform
reception in a best-effort manner. The service scenario 1 may be an
extended sensor scenario in which some receiving terminals
belonging to a specific range need to receive the same sensor
information from a transmitting terminal. In exemplary embodiments,
the transmitting terminal may refer to a terminal transmitting
data, and the receiving terminal may refer to a terminal receiving
data.
[0112] When the number of receiving terminals in the sidelink group
is limited and a service scenario 2 is supported, each of all the
receiving terminals belonging to the sidelink group may report
HARQ-ACK for data individually through a separate PSFCH. This
scheme may be a groupcast HARQ-ACK feedback option 2. In the
service scenario 2, since PSFCH resources are sufficient, the
transmitting terminal may perform monitoring on HARQ-ACK feedbacks
of all the receiving terminals belonging to the sidelink group, and
data reception may be guaranteed at all the receiving terminals
belonging to the sidelink group.
[0113] In addition, data reliability at the receiving terminal may
be improved by appropriately adjusting a transmit power of the
transmitting terminal according to a transmission environment.
Interference to other terminals may be mitigated by appropriately
adjusting the transmit power of the transmitting terminal. Energy
efficiency can be improved by reducing unnecessary transmit power.
A power control scheme may be classified into an open-loop power
control scheme and a closed-loop power control scheme. In the
open-loop power control scheme, the transmitting terminal may
determine the transmit power in consideration of configuration, a
measured environment, etc. In the closed-loop power control scheme,
the transmitting terminal may determine the transmit power based on
a transmit power control (TPC) command received from the receiving
terminal.
[0114] It may be difficult due to various causes including a
multipath fading channel, interference, and the like to predict a
received signal strength at the receiving terminal. Accordingly,
the receiving terminal may adjust a receive power level (e.g.,
receive power range) by performing an automatic gain control (AGC)
operation to prevent a quantization error of the received signal
and maintain a proper receive power. In the communication system,
the terminal may perform the AGC operation using a reference signal
received from the base station. However, in the sidelink
communication (e.g., V2X communication), the reference signal may
not be transmitted from the base station. That is, in the sidelink
communication, communication between terminals may be performed
without the base station. Therefore, it may be difficult to perform
the AGC operation in the sidelink communication. In the sidelink
communication, the transmitting terminal may first transmit a
signal (e.g., reference signal) to the receiving terminal before
transmitting data, and the receiving terminal may adjust a receive
power range (e.g., receive power level) by performing an AGC
operation based on the signal received from the transmitting
terminal. Thereafter, the transmitting terminal may transmit
sidelink data to the receiving terminal. The signal used for the
AGC operation may be a signal duplicated from a signal to be
transmitted later or a signal preconfigured between the
terminals.
[0115] A time period required for the ACG operation may be 15 vs.
When a subcarrier spacing of 15 kHz is used in the NR system, a
time period (e.g., length) of one symbol (e.g., OFDM symbol) may be
66.7 .mu.s. When a subcarrier spacing of 30 kHz is used in the NR
system, a time period of one symbol (e.g., OFDM symbol) may be 33.3
.mu.s. In the following exemplary embodiments, a symbol may mean an
OFDM symbol. That is, a time period of one symbol may be twice or
more than a time period required for the ACG operation.
[0116] For sidelink communication, it may be necessary to transmit
a data channel for data transmission and a control channel
including scheduling information for data resource allocation. In
sidelink communication, the data channel may be a physical sidelink
shared channel (PSSCH), and the control channel may be a physical
sidelink control channel (PSCCH). The data channel and the control
channel may be multiplexed in a resource domain (e.g., time and
frequency resource domains).
[0117] FIG. 9 is a conceptual diagram illustrating exemplary
embodiments of a method for multiplexing a control channel and a
data channel in sidelink communication.
[0118] Referring to FIG. 9, sidelink communication may support an
option 1A, an option 1B, an option 2, and an option 3. When the
option 1A and/or the option 1B is supported, a control channel and
a data channel may be multiplexed in the time domain. When the
option 2 is supported, a control channel and a data channel may be
multiplexed in the frequency domain. When the option 3 is
supported, a control channel and a data channel may be multiplexed
in the time and frequency domains. The sidelink communication may
basically support the option 3.
[0119] In the sidelink communication (e.g., NR-V2X sidelink
communication), a basic unit of resource configuration may be a
subchannel. The subchannel may be defined with time and frequency
resources. For example, the subchannel may be composed of a
plurality of symbols (e.g., OFDM symbols) in the time domain, and
may be composed of a plurality of resource blocks (RBs) in the
frequency domain. The subchannel may be referred to as an RB set.
In the subchannel, a data channel and a control channel may be
multiplexed based on the option 3.
[0120] In the sidelink communication (e.g., NR-V2X sidelink
communication), transmission resources may be allocated based on a
mode 1 or a mode 2. When the mode 1 is used, a base station may
allocate sidelink resource(s) for data transmission within a
resource pool to a transmitting terminal, and the transmitting
terminal may transmit data to a receiving terminal using the
sidelink resource(s) allocated by the base station. Here, the
transmitting terminal may be a terminal that transmits data in
sidelink communication, and the receiving terminal may be a
terminal that receives the data in sidelink communication.
[0121] When the mode 2 is used, a transmitting terminal may
autonomously select sidelink resource(s) to be used for data
transmission by performing a resource sensing operation and/or a
resource selection operation within a resource pool. The base
station may configure the resource pool for the mode 1 and the
resource pool for the mode 2 to the terminal(s). The resource pool
for the mode 1 may be configured independently from the resource
pool for the mode 2. Alternatively, a common resource pool may be
configured for the mode 1 and the mode 2.
[0122] Hereinafter, methods for coordination and allocation of one
or more sidelink resources in a communication system will be
described. Even when a method (e.g., transmission or reception of a
signal) to be performed at a first communication node among
communication nodes is described, a corresponding second
communication node may perform a method (e.g., reception or
transmission of the signal) corresponding to the method performed
at the first communication node. That is, when an operation of a
transmitting terminal is described, a corresponding receiving
terminal may perform an operation corresponding to the operation of
the transmitting terminal. Conversely, when an operation of a
receiving terminal is described, a corresponding transmitting
terminal may perform an operation corresponding to the operation of
the receiving terminal.
[0123] When the mode 1 is used, the base station may schedule a
resource used for sidelink data transmission to the transmitting
terminal, and the transmitting terminal may transmit sidelink data
to the receiving terminal by using the resource scheduled by the
base station. Therefore, a resource collision between terminals may
be prevented. When the mode 2 is used, the transmitting terminal
may select an arbitrary resource by performing a resource sensing
operation and/or resource selection operation, and may transmit
sidelink data by using the selected arbitrary resource. Since the
above-described procedure is performed based on an individual
resource sensing operation and/or resource selection operation of
each transmitting terminal, a collision between selected resources
may occur. Therefore, even when the mode 2 is used, as in the mode
1, a coordination operation of resources for data transmission and
reception between terminals, an operation of configuring a terminal
performing the coordination operation, an operation of configuring
a terminal notifying a resource(s) according to the coordination
operation, data transmission/reception operations between terminals
using the coordinated resources, and the like may be performed.
When the above-described operations are performed, collisions
between resources may be reduced, and communication performance may
be improved. When a resource sensing operation and/or resource
selection operation are performed within restricted resources
(e.g., coordinated resources), energy efficiency may be
improved.
[0124] When the mode 2 is used, a terminal in charge of resource
coordination and/or allocation for data transmission and reception
between terminals may be selected. When the resource coordination
and/or allocation is performed by the selected terminal, collision
between resources in sidelink communication may be reduced. Various
scenarios supporting the above-described operations may exist. In
groupcast communication (i.e., groupcast sidelink communication),
`communication between member terminals belonging to a groupcast
group` and/or `communication between a member terminal belonging to
a groupcast group and a terminal not belonging to the groupcast
group` may be performed. A transmitting terminal in the groupcast
communication (hereinafter referred to as a `groupcast (GC)
transmitting terminal`) may perform a resource coordination and/or
allocation operation for the communication between member terminals
belonging to the groupcast group and/or the communication between a
member terminal belonging to the groupcast group and a terminal not
belonging to the groupcast group. The GC transmitting terminal may
be referred to as a `coordinating` terminal.
[0125] In exemplary embodiments, methods in which a GC transmitting
terminal periodically transmits information on resources suitable
for communication to member terminals in a groupcast group will be
proposed. The GC transmitting terminal may transmit information on
resources available for the communication between member terminals
belonging to the groupcast group` and/or the communication between
a member terminal belonging to the groupcast group and a terminal
not belonging to the groupcast group as well as sidelink data for
its own groupcast communication. Specifically, the GC transmitting
terminal may recognize all member terminals in the groupcast group.
In this case, the GC transmitting terminal may individually
configure a usable resource region according to a member ID of each
of the member terminals in the groupcast group, and may transmit
information on the configured resource. The member ID may be a
unique ID for identifying the corresponding member terminal within
the groupcast group.
[0126] When a resource region includes a plurality of resource
sets, the GC transmitting terminal may configure one or more
resource sets to each of the member terminals in the groupcast
group, and transmit information related to the one or more resource
sets. Each of the member terminals in the sidelink group may
receive the resource information from the GC transmitting terminal,
select some resources (e.g., resource set) by performing a resource
sensing and/or selection operation or a random selection operation
on the resource set(s) indicated by the resource information, and
perform sidelink communication by using the selected resources. In
exemplary embodiments, the resource sensing and/or selection
operation may refer to a `resource sensing operation`, a `resource
selection operation`, or a `resource sensing operation and resource
selection operation`.
[0127] FIG. 10 is a conceptual diagram illustrating a first
exemplary embodiment of a method for configuring a resource
set(s).
[0128] As shown in FIG. 10, a resource pool for the mode 2 may be
configured independently of a resource pool for the mode 1. When
the mode 2 is used, a resource region (e.g., resource pool) for
transmission and reception of sidelink data may be divided into a
plurality of resource sets, and one or more resource sets may be
allocated to member terminal(s) (e.g., one member terminal) within
a sidelink group. The resource set(s) configured for the member
terminal may be associated with (or mapped to) to a member ID of
the member terminal. That is, a mapping relationship (e.g.,
association relationship) between resource set index(es) and a
member ID may be configured. The resource set(s) of the member
terminals may be signaled based on the mapping relationship between
resource set index(es) and member IDs.
[0129] Specifically, the GC transmitting terminal may transmit a
combination of {member ID, resource set index}. When it is possible
to allocate a plurality of resource sets to one member terminal, a
combination form of {member ID, resource set index #A, resource set
index #B, resource set index #C} may be signaled. A signaling
operation for a plurality of member terminals may be performed in a
form combined in the order of member IDs. The GC transmitting
terminal may transmit configuration information of resource set(s)
for a plurality of member terminals by using a groupcast scheme.
The configuration information of the resource set(s) may be
included in 1.sup.st sidelink control information (SCI), 2.sup.nd
SCI, and/or sidelink data.
[0130] The maximum number of allocable resource sets may be
pre-configured. When resource sets as many as the maximum number of
allocable resource sets are not configured, a field corresponding
to an unconfigured resource set (e.g., unallocated resource set)
may be configured to a specific value (e.g., a specific resource
set index, a binary number comprising all `0`s (e.g., `000 . . .
000`), or a binary number comprising all `1`s (e.g., `111 . . .
111`)). For example, when the maximum number of allocable resource
sets is 3 and two resource sets (e.g., resource sets #A and #B) are
configured, the GC transmitting terminal may configure {member ID,
resource set index #A, resource set index #B, `111 . . . 111`}, and
may signal the configured information (e.g., {member ID, resource
set index #A, resource set index #B, `111 . . . 111`}).
[0131] Alternatively, when member IDs are sequentially configured,
member IDs mapped to resource set indexes may not be signaled. In
this case, the GC transmitting terminal may inform the member
terminal(s) of the configuration information of the resource set(s)
without member IDs through the signaling. The member terminal(s)
may receive the configuration information from the GC transmitting
terminal, and identify (or select) resource set(s) for itself in
consideration of the order of the member IDs among the resource
set(s) indicated by the configuration information.
[0132] Some resources within the allocated resource set(s) may be
used for actual data transmission. In this case, the member
terminal(s) in the sidelink group may select a resource (e.g.,
resource region) by performing a resource sensing and/or selection
operation or a random selection operation within the resource
set(s), and perform sidelink communication by using the selected
resource. The operation performed for resource selection within a
resource set (e.g., resource sensing and/or selection operation or
random selection operation) may be configured by system information
and/or an RRC message. The system information and/or RRC messages
may be transmitted from the base station. The GC transmitting
terminal may inform the member terminal(s) of the operation to be
performed for resource selection within the resource set. In this
case, the operation performed for resource selection within the
resource set may be configured by the GC transmitting terminal. The
GC transmitting terminal may inform the operation to be performed
for resource selection within the resource set together with the
resource information (e.g., resource allocation information).
[0133] In a sidelink group, one or more resource sets may be
allocated to a member terminal. In this case, the member terminal
may perform sidelink communication with another member terminal
belonging to the sidelink group or another terminal not belonging
to the sidelink group by using resource(s) belonging to the one or
more resource sets. When communication is performed between member
terminals belonging to the sidelink group, resource sets allocated
to the member terminals may be shared, and sidelink communication
between the member terminals may be performed using the shared
resource sets. For example, in the exemplary embodiment shown in
FIG. 10, a terminal A and a terminal C may be member terminals
belonging to a sidelink group. For sidelink communication between
the terminal A and the terminal C, resource sets #0 and #1
allocated to the terminal A and a resource set #3 allocated to the
terminal C may be shared with each other. The terminal A and
terminal C may select resource(s) by performing a resource sensing
and/or selection operation or a random selection operation in all
the resource sets #0, #1, and #3, and sidelink communication
between the terminal A and the terminal C may be performed using
the selected resource(s).
[0134] The terminal A and terminal C may perform a monitoring
operation for data reception in all of the resource sets #0, #1,
and #3. According to the above-described method, sidelink resources
may be used efficiently. For example, when only the resource set #3
is allocated to the terminal C without sharing the resource sets #0
and #1 and more resources than the resource set #3 are required for
data transmission of the terminal C, a data transmission latency
may occur in the terminal C. However, when the terminal C shares
resources with the terminal A, the terminal C may use the resource
sets #0, #1, and #3 for data transmission. Accordingly, the
terminal C may transmit data without a transmission latency.
[0135] When data (e.g., sidelink data) can be transmitted through
consecutive subchannels in the frequency domain and resources
required for data transmission are small, each of the terminal A
and terminal C may select a suitable resource by performing a
resource sensing and/or selection operation or a random selection
operation in the resource set #3 or the resource sets #0 and #1,
and may perform sidelink communication by using the selected
suitable resource. The suitable resource may be referred to as a
`recommended resource` or `preferred resource`. When data (e.g.,
sidelink data) can be transmitted through consecutive subchannels
in the frequency domain and resources required for data
transmission are large, each of the terminal A and terminal C may
select a suitable resource by performing a resource sensing and/or
selection operation or a random selection operation in the resource
sets #0 and #1 instead of the resource set #3, and may perform
sidelink communication by using the selected suitable resource.
When data transmission is possible through non-consecutive
subchannels in the frequency domain, each of the terminal A and
terminal C may select a suitable resource by performing a resource
sensing and/or selection operation or a random selection operation
in the resource sets #0, #1, and #3, and may perform sidelink
communication by using the selected suitable resource.
[0136] Alternatively, in sidelink communication between member
terminals in a sidelink group, each member terminal may transmit
data only within a resource set allocated to it. For example, in
the exemplary embodiment shown in FIG. 10, when sidelink
communication between the terminal A and the terminal C, which are
member terminals, is performed in the sidelink group, the terminal
A may use the resource sets #0 and #1 allocated to itself to
transmit data, and the terminal C may use the resource set #3
allocated to itself to transmit data. The terminal A may perform
monitoring for data reception in the resource set #3 allocated to
the terminal C, and the terminal C may perform monitoring for data
reception in the resource sets #0 and #1 allocated to the terminal
A. When the terminal (e.g., member terminal) performs a resource
sensing and/or selection operation for data transmission based on
the above-described method, the size of the resource region in
which the resource sensing and/or selection operation is performed
may be restricted. In addition, the size of the resource region in
which a monitoring operation for data reception is performed may be
restricted. In this case, the complexity of the terminal may be
reduced, and energy efficiency may be increased.
[0137] In sidelink communication between member terminals in a
sidelink group, a member terminal may identify its own member ID
and/or a member ID of a counterpart member terminal by a PC5-RRC
connection configuration procedure and/or a signaling procedure by
a GC transmitting terminal. The member terminal may identify
resource information (e.g., resource set information) associated
with the member ID based on the resource allocation information
obtained from the GC transmitting terminal.
[0138] In the exemplary embodiment shown in FIG. 10, a plurality of
resource sets may be configured not to overlap each other in the
time-frequency domain within the resource pool. Alternatively, in
order to improve resource efficiency, a plurality of resource sets
may be configured to overlap in the time-frequency domain. In the
exemplary embodiment shown in FIG. 10, the same time resource may
be allocated to all terminals. It may be possible to allocate
different time resources to the member terminals so that a
half-duplex issue in which data transmission/reception times
overlap between the member terminals does not occur.
[0139] The GC transmitting terminal may periodically transmit
resource allocation information (e.g., configuration information of
the plurality of resource sets) to the member terminals in the
sidelink group. Alternatively, the resource allocation information
may be transmitted when a previously allocated resource set is
changed. In this case, the resource allocation information may
include only changed information. Accordingly, a signaling overhead
of the resource allocation information may be reduced.
[0140] Alternatively, when a request for resource allocation is
received from a member terminal belonging to the sidelink group,
the GC transmitting terminal may transmit resource allocation
information. A resource region (e.g., resource set) may be divided
into units of time and frequency resources having a predetermined
size. The resource region (e.g., resource set, time and frequency
resources) may be divided according to a certain resource pattern.
That is, the division unit of the resource region may be a time and
frequency resource or a resource pattern. In this case, the GC
transmitting terminal may allocate one or more resource regions to
each member terminal. When a plurality of resource regions are
allocated, the member terminal may randomly select a resource
region(s) from among the plurality of resource regions, and may
transmit data by using the selected resource region(s).
[0141] FIG. 11 is a conceptual diagram illustrating a first
exemplary embodiment of a resource pattern for time and frequency
resources.
[0142] As shown in FIG. 11, a resource region (e.g., resource set)
may be divided into time and frequency resources each having a
predetermined size. For example, a TF may refer to one time and
frequency resource having a predetermined size. TFs may be
configured to be randomly distributed according to a specific
pattern in the time and frequency domain. Each of TF0, TF1, TF2,
TF3, TF4, TF5, TF6, TF7, and TF8 may be one resource pattern. One
or more resource patterns may be allocated to each terminal (e.g.,
each member terminal). Information on one or more resource patterns
may be included in the resource allocation information (e.g.,
resource coordination information). The terminal may randomly
select a resource from within the allocated resource pattern(s),
and may transmit actual data using the selected resource. The
above-described method of configuring and transmitting the resource
allocation information (e.g., resource coordination information)
may be applicable not only to groupcast communication but also to
unicast communication and/or broadcast communication. In unicast
communication, a transmitting terminal may transmit resource
allocation information to a receiving terminal using PC5-RRC
signaling.
[0143] In a scenario supporting unicast communication, groupcast
communication, and broadcast communication, for sidelink
communication between terminals, a terminal (hereinafter referred
to as a `coordinating terminal`) performing a resource coordination
and/or allocation function may be configured, and the coordinating
terminal may perform a resource coordination and/or allocation role
for sidelink communication between terminals. The coordinating
terminal may be a transmitting terminal or a receiving terminal.
The coordinating terminal may be the above-described GC
transmitting terminal. Alternatively, the coordinating terminal may
be a third terminal other than the transmitting terminal and the
receiving terminal. The third terminal may be selected from among
terminals adjacent to the transmitting terminal or terminals
adjacent to the receiving terminal.
[0144] "When the coordinating terminal is the transmitting
terminal" or "when the coordinating terminal is selected from among
terminals adjacent to the transmitting terminal", the coordinating
terminal may inform information on resources suitable for sidelink
transmission, and may inform information on resources not suitable
for sidelink transmission. The above-described information may be
transmitted from the coordinating terminal to the transmitting
terminal. The resources that are not suitable may be referred to as
`non-recommended resources` or `non-preferred resources`. When the
coordinating terminal is the receiving terminal or the coordinating
terminal is selected from among terminals adjacent to the receiving
terminal, the coordinating terminal may inform information on
resources suitable for receiving sidelink data, and may inform
information on resources that are not suitable for receiving
sidelink data. The above-described information may be transmitted
from the coordinating terminal to the transmitting terminal.
[0145] The above-described information may be configured according
to the size of available resources and/or resource pool. For
example, when the size of resource coordination information (e.g.,
resource allocation information) is limited, the type of
information suitable for the size may be selected, and the selected
information may be transmitted. Whether the above-described
information is information on resources suitable for sidelink
communication (e.g., sidelink transmission and/or reception) or
information on resources not suitable for sidelink communication
may be preconfigured. The information type (e.g., information on
resources suitable for sidelink communication or information on
resources not suitable for sidelink communication) may be
configured by system information, RRC signaling (e.g., UE-specific
RRC signaling), a MAC control element (CE), and/or control
information (e.g., downlink control information (DCI), SCI).
Alternatively, the information type may be indicated by a separate
indicator. In this case, the information type may be signaled
together with the resource coordination information (e.g., resource
allocation information).
[0146] The transmitting terminal may select resource(s) to be used
for sidelink data transmission based on the resource coordination
information, and may transmit sidelink data by using the selected
resource(s). When the resource coordination information is
information on resources suitable for sidelink communication (e.g.,
sidelink transmission and/or reception), the resource(s) indicated
by the resource coordination information may be used for sidelink
data transmission as they are. In addition, the resource(s)
indicated by the resource coordination information may be used
after performing a re-evaluation operation for identifying whether
there is a collision due to aperiodic data transmission of another
terminal or a pre-emption operation for identifying whether the
corresponding resource(s) is pre-empted due to transmission of data
having a higher priority than that of another terminal. In
addition, a selection operation (e.g., resource sensing and/or
selection operation or random selection operation) of a
transmission resource of sidelink data within the resources
indicated by the resource coordination information may be
additionally performed.
[0147] When the resources indicated by the resource coordination
information are resources suitable for data transmission, the
transmitting terminal may perform data transmission based on the
resource coordination information. If a ratio of the resources
indicated by the resource coordination information among all the
resources is greater than or equal to a specific ratio (e.g., X %),
the transmitting terminal may select resources to be used for
actual transmission within the resources (e.g., candidate
resources) indicated by the resource coordination information, and
may perform data transmission using the selected resources. If the
ratio of the resources indicated by the resource coordination
information among all the resources is less than the specific ratio
(e.g., X %), the transmitting terminal may determine all candidate
resources that are a union of the resources (e.g., candidate
resources) indicated by the resource coordination information and
the candidate resources secured by the additional resource sensing
operation, select resource to be used for actual transmission among
all the candidate resources, and perform data transmission using by
the selected resources.
[0148] The specific ratio (e.g., X %) may be configured by system
information, RRC signaling (e.g., UE-specific RRC signaling), MAC
CE, and/or control information (e.g., DCI, SCI). Alternatively,
regardless of whether the ratio of the resources (e.g., candidate
resources) indicated by the resource coordination information among
all the resources is equal to or greater than the specific ratio,
the transmitting terminal may select the resources to be used for
actual transmission within the candidate resources, and perform
data transmission by using the selected resources. In addition, the
transmitting terminal may determine all candidate resources that
are a union of the candidate resources indicated by the resource
coordination information and the candidate resources secured by the
additional resource sensing operation, select resources to be used
for actual transmission among all the candidate resources, and
perform data transmission by using the selected resources. Whether
to apply the additional candidate resources secured by the
additional resource sensing operation may be determined according
to a sensing capability of the terminal. For example, a terminal
that cannot perform a resource sensing operation may select
resources to be used for actual transmission by using only the
resource coordination information. A terminal capable of performing
a resource sensing operation may select resources to be used for
actual transmission among the resources secured by the resource
sensing operation as well as the resources indicated by the
resource coordination information.
[0149] When both the resource coordination information and the
result of the additional resource sensing operation exist, priority
of resource selection may be required in the resource selection
procedure. For example, if an overlapped resource(s) between the
resources (e.g., resource region) indicated by the resource
coordination information and the resources (e.g., resource region)
according to the result of the additional resource sensing
operation exists, the overlapped resource(s) may have a highest
priority. The overlapped resource(s) may mean common resource(s) or
same resource(s) between the resources indicated by the resource
coordination information and the resources according to the result
of the additional resource sensing operation. The priority of the
resource coordination information may be configured to be higher
than the priority of the result of the additional resource sensing
operation, and in this case, the resources indicated by the
resource coordination information may be preferentially selected.
The priority of the result of the additional resource sensing
operation may be configured to be higher than the priority of the
resource coordination information, and in this case, the resources
according to the result of the additional resource sensing
operation may be preferentially selected. The resources may be
selected from a union or intersection of the resources indicated by
the resource coordination information and the resources according
to the result of the additional resource sensing operation. This
operation may be performed when the priority of the resource
coordination information is the same as the priority of the result
of the additional resource sensing operation.
[0150] When the additional resource sensing operation is performed
on resources other than the resource region indicated by the
resource coordination information, the priority of the resource
coordination information may be configured to be the same as the
priority of the result of the additional resource sensing
operation. Alternatively, one of the resource coordination
information and the result of the additional resource sensing
operation may have a relatively high priority. The above-mentioned
priority may be pre-configured. For example, the above-mentioned
priority may be configured by system information, RRC signaling,
MAC CE, and/or control information. That is, information indicating
the above-described priority may be transmitted to the terminal
(e.g., transmitting terminal).
[0151] In addition, whether to apply the additional candidate
resources secured through the resource sensing operation may depend
on configuration of the coordinating terminal. For example, when
one coordinating terminal provides resource coordination
information to a plurality of terminals, it may be preferable for
the plurality of terminals to select resources to be used for
actual transmission within the resources indicated by the resource
coordination information. For example, when a plurality of
terminals select resources to be used for actual transmission from
among the resources indicated by the resource coordination
information and the resources secured through the additional
resource sensing operation, since coordination on the resources
secured through the additional resource sensing operation was not
performed, a resource collision may occur between the plurality of
terminals. In this case, it may be preferable for each of the
plurality of terminals to select resources by referring only to the
resource coordination information obtained from the coordinating
terminal.
[0152] It may be difficult for the terminals receiving the resource
coordination information to determine whether the resource
coordination information is information that has been obtained by
coordination between a plurality of terminals. Therefore, it may be
preferable to signal a separate indicator indicating whether the
resource coordination information is information that has been
coordinated between a plurality of terminals. For example, an
indicator having a size of 1 bit may indicate whether the resource
coordination information is information that has been coordinated
between a plurality of terminals. That is, the indicator may
instruct the terminal to perform communication in consideration of
only the resource coordination information or to perform
communication in consideration of the result of the additional
resource sensing operation as well as the resource coordination
information. The indicator may be transmitted in advance to each of
the terminals through separate signaling. Alternatively, the
indicator may be signaled to each of the terminals together with
the resource coordination information. Resources coordinated
between a plurality of terminals may refer to resources in which a
collision does not occur between the plurality of terminals.
[0153] Even when performing of communication in consideration of
the result of the additional resource sensing operation as well as
the resource coordination information is indicated, the terminal
without resource sensing capability may perform a resource
selection operation using only the resource coordination
information. When the resources indicated by the resource
coordination information are resources not suitable for data
transmission, the transmitting terminal may perform data
transmission based on the resource coordination information. That
is, since the resources indicated by the resource coordination
information are resources not suitable for data transmission, the
transmitting terminal may perform a sensing operation in resources
other than the resource region indicated by the resource
coordination information, and may perform a resource selection
operation based on a result of the sensing operation. According to
the resource coordination information, resource regions in which
the sensing operation is performed may be reduced, and efficient
resource sensing may be possible. Since a resource region that is
not suitable for data transmission of a specific terminal may be
suitable for data transmission of another terminal, efficient
resource coordination between terminals may be possible.
Alternatively, the transmitting terminal may select resources by
performing a random selection operation within resources outside
the inappropriate resource region indicated by the resource
coordination information.
[0154] In another exemplary embodiment, the resource coordination
information may indicate information indicating whether a collision
actually occurs in the selected resource of the transmitting
terminal, information indicating whether a collision in the
selected resource of the transmitting terminal is predicted, or
information indicating whether a potential collision exists in the
selected resource of the transmitting terminal. For example, when a
resource actually used by the transmitting terminal for data
transmission collides with a resource used by another terminal, or
when a resource reserved by the transmitting terminal for data
transmission overlaps with a resource reserved by another terminal,
the coordinating terminal may identify a collision before or after
the actual collision, and inform the transmitting terminal of
collision-related information. If the resource coordination
information is collision-related information after a collision
occurs, the transmitting terminal receiving the resource
coordination information may determine whether to perform a
retransmission operation based on a HARQ-ACK (e.g., ACK or NACK)
received from the receiving terminal.
[0155] For example, even in case that a resource collision occurs
(e.g., even in case that the resource coordination information
indicates that an actual collision occurs), the transmitting
terminal may not perform a retransmission operation when ACK is
received from the receiving terminal. On the other hand, when NACK
is received from the receiving terminal, the transmitting terminal
may perform a retransmission operation on the corresponding data.
Alternatively, the receiving terminal may not be able to determine
whether data reception is successful, and may not be able to
transmit a HARQ-ACK for data to the transmitting terminal. In this
case, the receiving terminal may determine that a collision occurs
in the resource, and may transmit resource collision information to
the transmitting terminal. When the resource collision information
is received from the receiving terminal, the transmitting terminal
may perform reselection of the resource for retransmission and
retransmission of the data using the reselected resource.
Alternatively, the retransmission of the data may be performed
without the resource reselection.
[0156] When a HARQ-ACK feedback operation for data transmitted to
the receiving terminal is not supported (e.g., when the HARQ-ACK
feedback operation is disabled), the transmitting terminal may
perform a retransmission operation based on the collision-related
information indicated by the resource coordination information. For
example, when the resource coordination information indicates that
a resource collision has occurred (e.g., when information
indicating that an actual collision has occurred is obtained from
the resource coordination information), the transmitting terminal
may perform reselection of the resource for retransmission and a
retransmission operation for the data using the reselected
resource. Alternatively, the retransmission of the data may be
performed without the resource reselection. On the other hand, when
the resource coordination information does not indicate that a
resource collision has occurred, the transmitting terminal may not
perform a retransmission operation. When the resource coordination
information indicates information on a potential collision, the
transmitting terminal may perform a transmission resource
reselection operation based on the resource coordination
information.
[0157] After transmission of the resource coordination information,
an application time of the resource coordination information may be
configured differently according to the type of resource
coordination information. Specifically, the application time of the
resource coordination information may be configured differently
according to a transmission pattern of the resource coordination
information in the time domain. In case that the resource
coordination information is transmitted periodically, the terminal
may perform a resource selection operation by applying the resource
coordination information after the reception of the resource
coordination information (e.g., reception time of the resource
coordination information+processing time) until a next period
reception/application time of resource coordination. In case that
the resource coordination information is transmitted aperiodically
(e.g., in case that the resource coordination information is
transmitted when a specific event occurs), the terminal may perform
a resource selection operation by applying the resource
coordination information until new resource coordination
information is received by occurrence of a next event. In case that
the resource coordination information is transmitted according to a
request (e.g., a request for data transmission), after receiving
the resource coordination information, the terminal may apply the
resource coordination information until a completion time of
initial transmission of the corresponding data or a completion time
of one or more retransmissions for the corresponding data.
[0158] The above-described resource coordination information
transmitted by the coordinating terminal may be information on a
resource used for actual transmission or information on resources
(e.g., recommended resources or non-recommended resources) to be
referenced to select a resource used for actual transmission.
Signaling methods for transmitting the resource coordination
information may be important. Accordingly, methods for expanding
and applying existing resource reservation information will be
proposed in exemplary embodiments. The transmitting terminal may
transmit information on a resource used for actual transmission or
information on a resource scheduled to be used for actual
transmission through a control channel. Information on up to three
resources may be transmitted on one control channel.
[0159] The transmitting terminal may transmit information on more
than three resources through one control channel. That is, the
maximum number of resources transmittable through one control
channel may be increased. In this case, the existing signaling
scheme may be reused, and thus signaling overhead may be reduced.
The maximum number (e.g., R.sub.MAX) of resources (e.g., resource
regions) that can be signaled through resource coordination
information may be pre-configured. Alternatively, R.sub.MAX may be
configured by system information, RRC signaling, MAC CE, and/or
control information (e.g., DCI, SCI). A resource for signaling of
the resource coordination information may be configured differently
from a resource used for actual transmission (e.g., data
transmission). Specifically, a unit of a resource used for
signaling of the resource coordination information may be
configured to be larger than a unit of a resource used for actual
transmission. The resource information (e.g., resource region,
subchannel size, resource pool, and so on) may be indicated by the
resource coordination information.
[0160] For example, a size of a subchannel for signaling of the
resource coordination information (e.g., a size of a subchannel
indicated by the resource coordination information) may be
configured to be larger than a size of a subchannel for data
transmission, and in this case, signaling overhead of resource
coordination information may be reduced. When the resource
coordination information indicates recommended resources (e.g.,
resources suitable for sidelink communication), resources used for
data transmission may be selected through a resource sensing and/or
selection operation or a random selection operation from among the
resources indicated by the resource coordination information. When
the resource coordination information indicates non-recommended
resources (e.g., resources not suitable for sidelink
communication), the resources used for actual data transmission may
be selected through a resource sensing and/or selection operation
or a random selection operation from among resources other than the
resource region indicated by the resource coordination information.
In order to configure a resource used for signaling of the resource
coordination information to be different from a resource used for
actual data transmission/reception, a resource pool for the
resource coordination information may be separately configured.
Configuration information of the resource pool for the resource
coordination information may be transmitted by system information
and/or RRC signaling. The resource coordination information may be
transmitted and received in the resource pool configured for the
resource coordination information. Alternatively, parameters (e.g.,
subchannel size and/or R.sub.ix) for signaling of the resource
coordination information may be added to the existing configuration
information of the resource pool for sidelink communication. The
resource pool may be indicated by the resource coordination
information.
[0161] FIG. 12 is a conceptual diagram illustrating a first
exemplary embodiment of configuration of a resource pool for
resource coordination.
[0162] As shown in FIG. 12, information on a resource for
transmission and reception of actual data may be configured
independently of information on a resource for signaling of the
resource coordination information. For example, a resource for
transmission and reception of data may be different from a resource
for transmission and reception of the resource coordination
information. A subchannel #1 may be used for transmission and
reception of data, and a subchannel #2 may be used for transmission
(e.g., signaling) of the resource coordination information. The
size of the subchannel #2 may be twice the size of the subchannel
#1. In this case, an overhead required for signaling of the
resource coordination information may be reduced. The resources
used for transmission and reception of data may be selected by
performing a resource sensing and/or selection operation or a
random selection operation in resources indicated by the resource
coordination information (e.g., recommended resources) and/or
resources not indicated by the resource coordination information
(e.g., non-recommended resources).
[0163] The size of the subchannel #2 for signaling of the resource
coordination information may be configured to n times the size of
the subchannel #1 for data transmission and reception. n may be a
natural number. The size of the subchannel #2 may not be accurately
set to n times the size of the subchannel #1. In this case, when
the size of the last resource region is greater than or equal to
the size of the subchannel #1 for data transmission and reception,
and the size of the last resource region is less than the size of
the subchannel #2 for transmission and reception of the resource
coordination information, the last resource region may be indicated
by signaling of the resource coordination information, and may be
used for transmission and reception of data.
[0164] A unit of a sensing operation performed by the coordinating
terminal for signaling of the resource coordination information may
be a unit of a subchannel for data transmission/reception, not a
unit of a subchannel for signaling the resource coordination
information. The resource coordination information may be signaled
in units of the subchannel #2, and the sensing operation performed
by the coordinating terminal for transmission of the resource
coordination information may be performed in units of the
subchannel #1. In the exemplary embodiment shown in FIG. 12, the
subchannel #2 may include two subchannels #1. A sensing result in
one subchannel #1 among two subchannels #1 may satisfy a resource
selection criterion. In this case, some or all of the resources
selected according to the sensing result may be used for data
transmission/reception. However, when the signaling unit is the
subchannel #2, the selected resources may not be used.
[0165] Accordingly, the resource coordination information may be
signaled in units of the subchannel #2, and a start position of the
resource coordination information may be selected in units of the
subchannel #1. An overhead by the above-described signaling method
may be increased than the signaling overhead when the start
position of the resource coordination information is selected in
units of the subchannel #2. However, when the above-described
signaling method is used, if one subchannel #1 among two
subchannels #1 in the subchannel #2 satisfies the resource
selection criterion, one subchannel #1 may be signaled. Therefore,
resource efficiency may be improved
[0166] Alternatively, not only the size of the subchannel through
which the resource coordination information is transmitted, but
also the start position of the resource coordination information
may be selected in units of the subchannel #2, and an offset may be
added to the start position of the subchannel #2. The offset may be
preferably set in units of the subchannel #1. For example, in the
exemplary embodiment shown in FIG. 12, the subchannel #2 includes
two subchannels #1, so an offset having a size of 1 bit may be
added, and the value of the offset may indicate 0 or 1.
[0167] Alternatively, the resource coordination information may be
signaled in form of a bitmap. A subchannel for signaling of the
resource coordination information in a slot (e.g., sidelink slot)
may be indicated by a bitmap. A subchannel for signaling of the
resource coordination information within a certain time period may
be indicated by a bitmap for each slot. A two-dimensional
bitmap-based signaling operation may be performed for all
subchannels in slots (e.g., sidelink slots) within a predetermined
time period. When a two-dimensional bitmap scheme is used,
signaling overhead may increase, and accurate resource coordination
information may be provided.
[0168] A sidelink HARQ-ACK feedback function may be used for the
resource coordination and/or allocation operation. In a sidelink
group performing groupcast communication, a GC transmitting
terminal may configure resources for member terminal(s) based on
groupcast HARQ-ACK feedback information. When the groupcast
HARQ-ACK feedback option 2 is used, each of all member terminals
belonging to the groupcast group may transmit HARQ-ACK (e.g.,
HARQ-ACK feedback information) through an individual PSFCH. The GC
transmitting terminal may receive a HARQ-ACK of each of the member
terminals belonging to the groupcast group, and may identify a
reception environment for each of the member terminals based on the
HARQ-ACK. Accordingly, the GC transmitting terminal may perform
resource configuration for the member terminals based on the
HARQ-ACK feedback information.
[0169] Specifically, a channel state of a member terminal reporting
ACK may be better than a channel state of a member terminal
reporting NACK. A distance between the member terminal reporting
ACK and the GC transmitting terminal may be shorter than a distance
between the member terminal reporting NACK and the GC transmitting
terminal. The GC transmitting terminal may allocate independent
resources to adjacent member terminals in order to reduce
interference between the adjacent member terminals. The distance
between the member terminal reporting NACK and the GC transmitting
terminal may be relatively long, and a distance between the member
terminals reporting NACK may be relatively close. Accordingly, the
GC transmitting terminal may allocate independent resources to
member terminals reporting NACK. Since a distance between a set of
member terminal(s) reporting ACK and a set of member terminal(s)
reporting NACK may be relatively long, interference may not be
large even when overlapping resources are configured between the
aforementioned sets. The HARQ-ACK feedback information may be used
to configure a pair between member terminals in the sidelink
group.
[0170] The HARQ-ACK feedback information may be used for the
resource coordination and/or allocation operation in unicast
communication or broadcast communication. When a HARQ-ACK reported
by a terminal receiving the resource coordination information is
ACK, the existing resource coordination information may be
maintained. When the HARQ-ACK reported by the terminal receiving
the resource coordination information is NACK, the resource
coordination information may be updated. In order to avoid frequent
updating of the resource coordination information, it may be
configured to update the resource coordination information when
NACK is continuously reported. The continuous NACKs may be n
consecutive NACKs or consecutive NACKs in a time period d. n may be
a natural number. The number n of consecutive NACKs and/or the time
period d may be configured by system information, RRC signaling,
MAC CE, and/or control information (e.g., DCI, SCI). If ACK occurs
while counting the number of NACKs, the number of NACKs or the time
period may be initialized. Alternatively, if ACK occurs while
counting the number of NACKs, counting of the number of NACKs may
be continued without initialization of the number of NACKs, and
when the number of counted NACKs is n or more, the resource
coordination information may be updated. If ACK occurs while
counting the number of NACKs, the measurement during the time
period may be continued without initialization of the time period,
and when the length of the measured time period is d or more, the
resource coordination information may be updated.
[0171] The resource coordination information may be updated
according to a request of the terminal. When it is determined that
the update of the resource coordination information is necessary,
the terminal may request transmission of the updated resource
coordination information by transmitting a triggering signal to the
coordinating terminal. A large power may not be required for a
monitoring operation of the triggering signal, and the triggering
signal may be reliably received by the coordinating terminal. A
channel (e.g., resource) through which the triggering signal is
transmitted may be designed to be the same as or similar to a
PSFCH. The PSFCH periodicity may be 1, 2, or 4 slots (e.g., logical
sidelink (SL) slots). The PSFCH may be repeatedly transmitted in
two symbols (e.g., two OFDM symbols) in a slot. Among the two
symbols, the first symbol may be used for automatic gain control
(AGC) for correctly adjusting a received power level of the
PSFCH.
[0172] The PSFCH may be transmitted using a frequency resource
region configured by system information and/or RRC signaling in
corresponding symbols. In the symbol(s) configured for PSFCH
transmission, a frequency resource region not used for PSFCH
transmission may be used for transmission of the triggering signal.
A frequency resource region used for transmission of the triggering
signal may be configured through system information and/or RRC
signaling (e.g., UE-specific RRC signaling). A transmission
resource of the triggering signal within the preconfigured resource
region may be implicitly configured based on an ID of the
coordinating terminal, an ID of the terminal receiving the resource
coordination information, and/or an ID of the terminal transmitting
the triggering signal. The terminal transmitting the triggering
signal may be a terminal independent from the terminal receiving
the resource coordination information.
[0173] Alternatively, the transmission resource of the triggering
signal may be explicitly configured by system information, RRC
signaling, MAC CE, and/or control information (e.g., DCI, SCI). In
a PC5-RRC connection establishment procedure between terminals for
unicast communication, information on the transmission resource for
the triggering signal may be signaled. When the resource
coordination information is periodically updated, when the
triggering signal is periodically transmitted, when the update of
the existing resource coordination information is not required, or
when additional resource coordination information is not required,
a signal (e.g., keeping signal) instructing to prohibit the update
of the resource coordination information may be transmitted
separately.
[0174] A channel (e.g., resource) through which the keeping signal
is transmitted may be designed to be the same as or similar to a
PSFCH. When the keeping signal is received, the coordinating
terminal may stop updating the resource coordination information.
In addition, the coordinating terminal may not transmit the
resource coordination information. In this case, signaling overhead
and power consumption for updating and transmitting the resource
coordination information may be reduced. When both the triggering
signal and the keeping signal are used, different cyclic shift
values may be applied to the triggering signal and the keeping
signal, and the triggering signal and the keeping signal may be
transmitted in the same resource region. Specifically, when a
cyclic shift=0 of a Zadoff-Chu sequence of length 12 transmitted in
a specific resource region is used for transmission of the
triggering signal, a cyclic shift=6 may be used for transmission of
the keeping signal.
[0175] FIG. 13 is a conceptual diagram illustrating a first
exemplary embodiment of a resource configuration method for a
triggering signal and/or a keeping signal.
[0176] As shown in FIG. 13, in symbol(s) according to a PSFCH
periodicity, a frequency resource region other than a frequency
resource region for PSFCH may be configured for transmission of a
triggering signal or a keeping signal. The frequency resource
region for transmission of a triggering signal or a keeping signal
may be configured as a localized region. As another scheme, since
resource blocks (RBs) in a bandwidth part (BWP) may be configured
by a bitmap, the frequency resource region for transmission of a
triggering signal or a keeping signal may be configured by a
bitmap.
[0177] Alternatively, without separate signaling for resource
configuration, a frequency resource region other than a frequency
resource region for PSFCH may be configured as the frequency
resource region for transmission of a triggering signal or a
keeping signal. A triggering signal and/or a keeping signal may be
transmitted in RB(s) or RB set(s) configured as the transmission
resource for each of triggering signal and keeping signal by
applying different cyclic shift values of the same Zadoff-Chu
sequence. In the exemplary embodiment shown in FIG. 13, when a
Zadoff-Chu sequence of length 12 is used in one RB, a cyclic
shift=0 may be applied to a triggering signal, and a cyclic shift=6
may be applied to a keeping signal. When a signaling unit is an RB
set including a plurality of RBs, a Zadoff-Chu sequence having a
length corresponding to the RB set may be used. In this case,
arbitrary cyclic shift values according to a length corresponding
to the RB set, which are other than the cyclic shift=0 or the
cyclic shift=6, may be used. The cyclic shift value(s) applied to
the triggering signal and/or the keeping signal may be configured
by system information, RRC signaling, MAC CE, and/or control
information.
[0178] When a resource collision between terminals is detected by a
third terminal or when a resource collision between terminals is
predicted by a third terminal, the third terminal may transmit a
collision indicator. The collision indicator may be configured
independently of the triggering signal and/or the keeping signal.
When the collision indicator is transmitted after a resource
collision is detected, a time interval between the time of
identifying the resource collision and the time of transmitting the
collision indicator may be fixed. Alternatively, the
above-described time interval may be pre-configured. For example,
the above-described time interval may be configured by system
information, RRC signaling, MAC CE, and/or control information.
[0179] Terminals including the two terminals in which the resource
collision has occurred may detect the collision indicator, and may
identify that the resource collision has occurred based on the
collision indicator. The resource coordination information may be
updated based on the collision indicator. Alternatively, the
retransmission of the resource coordination information may be
determined based on the collision indicator. When the resource
collision is predicted, a resource reselection operation may be
performed. A transmission resource of the collision indicator may
be configured in the same or similar manner as the transmission
resource of the triggering signal and/or the keeping signal. That
is, a channel (e.g., resource) through which the collision
indicator is transmitted may be designed to be the same as or
similar to a PSFCH. The collision indicator may be transmitted to
be distinguished from NACK according to the HARQ-ACK feedback
scheme.
[0180] Specifically, a cyclic shift for the collision indicator may
be added in a PSFCH resource in which a HARQ-ACK feedback is
transmitted. For example, if a cyclic shift=0 is applied to ACK and
a cyclic shift=6 is applied to NACK in a PSFCH resource, a cyclic
shift=8 for the collision indicator may be added. That is, a
collision indicator to which the cyclic shift=8 is applied may be
transmitted. The collision indicator for the resource collision
that has already occurred may be transmitted according to a
reporting periodicity of NACK (e.g., PSFCH periodicity). Since the
collision indicator may be generated faster than NACK, a
transmission periodicity of the collision indicator may be shorter
than the reporting periodicity of NACK (e.g., PSFCH periodicity).
The third terminal may be the coordinating terminal or an arbitrary
terminal that has detected the resource collision.
[0181] When the collision indicator is received, the coordinating
terminal may determine that the resource collision has occurred,
may update the resource coordination information, and may transmit
the updated resource coordination information. Alternatively, the
coordinating terminal may detect or predict the resource collision
between terminals without the collision indicator. In this case,
the coordinating terminal may update the resource coordination
information, and may transmit the updated resource coordination
information. Here, the coordinating terminal may determine whether
a resource collision has occurred by performing an interference
measurement operation and/or a sensing operation. When a collision
between a transmission resource of the transmitting terminal and a
transmission resource of another terminal is detected or predicted,
the coordinating terminal may update the resource coordination
information and transmit the updated resource coordination
information. The resource coordination information may be updated
to prevent the resource collision. Alternatively, the resource
coordination information may be automatically updated after a
pre-configured time. A timer for automatic update of the resource
coordination information may be pre-configured. For example, the
timer may be configured by system information, RRC signaling, MAC
CE, and/or control information. A timer value may be transmitted
through a control channel together with the resource coordination
information. After a time according to the timer elapses, the
coordinating terminal may transmit the updated resource
coordination information.
[0182] In the resource coordination information transmission
procedure, it may be necessary to set a priority of the resource
coordination information. In sidelink communication, priorities of
data units may be configured differently. When
transmission/reception timings of different data units are the
same, a transmission operation or a reception operation on a data
unit having a high priority may be performed. For transmission of a
data unit having a high priority, a transmission resource of a data
unit having a low priority may be pre-empted. In order to avoid a
case where a transmission resource of the resource coordination
information is pre-empted by transmission of a data unit of another
terminal or a case where transmission of the resource coordination
information is dropped according to a result of priority comparison
with other data units, it may be necessary to set an appropriate
priority.
[0183] Specifically, the priority may be configured differently
according to the type of the resource coordination information.
When the resource coordination information is used for sidelink
data transmission (e.g., when resources indicated by the resource
coordination information are used for data transmission as they are
or when resource(s) selected by a resource selection operation
within the resources indicated by the resource coordination
information are used for data transmission), the priority of the
corresponding resource coordination information may be configured
to the highest. Accordingly, it may be prevented that the
transmission of the corresponding resource coordination information
is dropped or that the transmission resource of the corresponding
resource coordination information is pre-empted.
[0184] Alternatively, a pre-emption operation between data units
may be configured, and the configured pre-emption operation may be
activated. In this case, the terminal may determine whether the
resource is pre-empted by comparing the priorities of the data
units. For example, when the priority of data (i.e., data unit) of
the terminal is lower than the priority of data of another
terminal, the terminal may determine that the transmission resource
of the corresponding data is pre-empted. The higher the priority
value, the lower the priority of the corresponding data. If the
priority value of data to be transmitted by the terminal is
prio.sub.TX, the priority value of data of another terminal is
prio.sub.RX, and `prio.sub.TX>prio.sub.RX` is satisfied, the
terminal may determine that the transmission resource of the data
is pre-empted.
[0185] The configured pre-emption operation may not be activated.
In this case, when the priority of another terminal data is higher
than those of the pre-configured specific priority and the priority
of the data to be transmitted by the terminal, the terminal may
determine that the transmission resource of the data is pre-empted.
That is, when the pre-configured specific priority is prio.sub.pre,
and `prio.sub.RX<prio.sub.pre` and `prio.sub.TX>prio.sub.RX`
are satisfied, the terminal may determine that the transmission
resource of the data is pre-empted. Therefore, it may be preferable
that the priority for the resource coordination information is
configured higher than a pre-emption threshold. For example, it may
be preferable that the priority for the resource coordination
information is configured to the highest.
[0186] In order to select a transmission resource of data, the
resource coordination information may be used as a reference. That
is, the terminal may not necessarily use the resource coordination
information. In this case, in order to prevent a transmission
resource of the resource coordination information from being
pre-empted, it is not necessary to set the priority of the resource
coordination information to the highest priority or a priority
higher than the pre-emption threshold. The priority of the resource
coordination information may be appropriately set according to an
operating environment of the communication system. The resource
coordination information may be transmitted through SCI (e.g.,
1.sup.st SCI, 2.sup.nd SCI, or a new control channel) other than a
PSSCH. By applying the above-mentioned priority, the priority of
the resource coordination information may be configured to be the
same as the priority of the data.
[0187] The exemplary embodiments of the present disclosure may be
implemented as program instructions executable by a variety of
computers and recorded on a computer readable medium. The computer
readable medium may include a program instruction, a data file, a
data structure, or a combination thereof. The program instructions
recorded on the computer readable medium may be designed and
configured specifically for the present disclosure or can be
publicly known and available to those who are skilled in the field
of computer software.
[0188] Examples of the computer readable medium may include a
hardware device such as ROM, RAM, and flash memory, which are
specifically configured to store and execute the program
instructions. Examples of the program instructions include machine
codes made by, for example, a compiler, as well as high-level
language codes executable by a computer, using an interpreter. The
above exemplary hardware device can be configured to operate as at
least one software module in order to perform the embodiments of
the present disclosure, and vice versa.
[0189] While the embodiments of the present disclosure and their
advantages have been described in detail, it should be understood
that various changes, substitutions and alterations may be made
herein without departing from the scope of the present
disclosure.
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